Melanotan II

Hypoactive Sexual Desire Disorder in Women: Physiology, Assessment, Diagnosis, and Treatment.

Nearly half of women in the United States report problems with sexual function. Many health care providers do not ask about sexual concerns during routine clinical encounters because of personal discomfort, lack of familiarity with treatment, or the belief that they lack adequate time to address this complex issue. This may be especially true for hypoactive sexual desire disorder (HSDD), the most commonly identified sexual problem among women. HSDD is characterized by a deficiency of sexual thoughts, feelings, or receptiveness to sexual stimulation that has been present for at least 6 months, causes personal distress, and is not due to another medical condition. This is an up-to-date overview of HSDD for clinicians, discussing its physiology, assessment, diagnosis, and treatment strategies. Although a definitive physiology of HSDD is still unknown, multiple hormones and neurotransmitters likely participate in a dual-control model to balance excitation and inhibition of sexual desire. For assessment and diagnosis, validated screening tools are discussed, and the importance of a biopsychosocial assessment is emphasized, with guidance on how this can be implemented in clinical encounters. The 2 recently approved medications for HSDD, flibanserin and bremelanotide, are reviewed as well as off-label treatments. Overall, HSDD represents a common yet likely underrecognized disorder that midwives and other health care providers who care for women across the life span are in a unique position to address.

Bremelanotide: First Approval.

Bremelanotide (Vyleesi™) is a melanocortin receptor agonist recently approved in the USA for the treatment of premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD), as characterized by low sexual desire that causes marked distress or interpersonal difficulty. It is a self-administered, on-demand subcutaneous therapy. Initially developed by Palatin Technologies who sponsored the Phase 3 clinical trials, bremelanotide was subsequently out-licensed to AMAG Pharmaceuticals Inc. for exclusive North American rights to develop and commercialize the drug, including submitting the New Drug Application to the US FDA. Bremelanotide is a synthetic peptide analogue of the neuropeptide hormone alpha melanocyte-stimulating hormone (α-MSH) with high affinity for the melanocortin type 4 receptor (thought to be important for sexual function), giving it the potential to modulate brain pathways involved in sexual response. This article summarizes the milestones in the development of bremelanotide leading to this first regulatory approval.

Metallothionein in Brain Disorders.

Metallothioneins are a family of proteins which are able to bind metals intracellularly, so their main function is to regulate the cellular metabolism of essential metals. There are 4 major isoforms of MTs (I-IV), three of which have been localized in the central nervous system. MT-I and MT-II have been localized in the spinal cord and brain, mainly in astrocytes, whereas MT-III has been found mainly in neurons. MT-I and MT-II have been considered polyvalent proteins whose main function is to maintain cellular homeostasis of essential metals such as zinc and copper, but other functions have also been considered: detoxification of heavy metals, regulation of gene expression, processes of inflammation, and protection against free radicals generated by oxidative stress. On the other hand, the MT-III has been related in events of pathogenesis of neurodegenerative diseases such as Parkinson and Alzheimer. Likewise, the participation of MTs in other neurological disorders has also been reported. This review shows recent evidence about the role of MT in the central nervous system and its possible role in neurodegenerative diseases as well as in brain disorders.

Safety Profile of Bremelanotide Across the Clinical Development Program.

Background: Bremelanotide, a melanocortin receptor agonist, is Food and Drug Administration (FDA)-approved for the treatment of premenopausal women with acquired, generalized hypoactive sexual desire disorder. Methods: Review of bremelanotide's safety profile from the clinical development program (phases 1 through 3). Results: The clinical development program comprised 3500 subjects in 43 completed studies. In the phase 3 studies, subjects took bremelanotide for up to 18 months. The most common adverse events (AEs) were nausea (40.0% vs. 1.3%), flushing (20.3% vs. 1.3%), headache (11.3% vs. 1.9%), and injection site reactions (5.4 vs. 0.5), bremelanotide versus placebo groups, respectively, in the integrated double-blind portion of the phase 3 studies (N = 1247). Nausea was the most common reason for bremelanotide discontinuation. There were no deaths; a few subjects experienced serious AEs. Focal hyperpigmentation was rare when bremelanotide was dosed in accordance with label recommendations, but it occurred in more than one-third of subjects following up to 16 consecutive daily dosings. Small and transient but statistically significant blood pressure increases were observed during ambulatory blood pressure monitoring. Most drug-drug interactions were not clinically significant, except for interactions that lowered plasma concentrations of indomethacin and naltrexone. In the double-blind portion of the integrated phase 3 studies, 70% of the bremelanotide group proceeded to the open-label phase of the studies versus 87% of those on placebo. Conclusions: The AEs associated with bremelanotide are mostly mild to moderate. Although not deemed clinically important, bremelanotide should be used with caution in patients at risk of cardiovascular disease, and blood pressure should be well controlled during treatment. Clinical Trial Registration number: NCT02333071 [Study 301] and NCT02338960 [Study 302].

Bremelanotide for Treatment of Female Hypoactive Sexual Desire.

Hypoactive sexual desire disorder (HSDD) is a persistent deficiency or absence of sexual fantasies and desire resulting in significant distress or interpersonal difficulty. Women with this disorder may display a lack of motivation for sexual activity, reduced responsiveness to erotic cues, a loss of interest during sexual activity, and avoidance of situations that could lead to sexual activity. The pathophysiology of HSDD is thought to be centered around inhibitory and excitatory hormones, neurotransmitters, and specific brain anatomy. Due to the multifactorial nature of HSDD, treatment can be complex and must attempt to target the biological and psychosocial aspects of the disorder. Bremelanotide is a melanocortin receptor agonist and has been recently approved by the FDA to treat HSDD. Bremelanotide is administered intranasally or as a subcutaneous injection. The recommended dosage of bremelanotide is 1.75 mg injected subcutaneously in the abdomen or thigh at least 45 min before sexual activity. Studies showed improvements in desire, arousal, and orgasm scores when 1.75 mg of bremelanotide was administered before sexual activity compared to a placebo. Bremelanotide is a promising way to treat HSDD.

Targeting the central melanocortin system for the treatment of metabolic disorders.

A large body of preclinical and clinical data shows that the central melanocortin system is a promising therapeutic target for treating various metabolic disorders such as obesity and cachexia, as well as anorexia nervosa. Setmelanotide, which functions by engaging the central melanocortin circuitry, was approved by the FDA in 2020 for use in certain forms of syndromic obesity. Furthermore, the FDA approvals in 2019 of two peptide drugs targeting melanocortin receptors for the treatment of generalized hypoactive sexual desire disorder (bremelanotide) and erythropoietic protoporphyria-associated phototoxicity (afamelanotide) demonstrate the safety of this class of peptides. These approvals have also renewed excitement in the development of therapeutics targeting the melanocortin system. Here, we review the anatomy and function of the melanocortin system, discuss progress and challenges in developing melanocortin receptor-based therapeutics, and outline potential metabolic and behavioural disorders that could be addressed using pharmacological agents targeting these receptors.

Regulation of metallothionein gene expression.

The rapid and robust induction of metallothioneins (MT)-I and II by a variety of inducers that include heavy toxic metals, reactive oxygen species, and different types of stress provide a useful system to study the molecular mechanisms of this unique induction process. The specific expression of MT-III in the brain and of MT-IV in the squamous epithelium of skin and tongue offers a unique opportunity to identify and characterize the tissue-specific factors involved in their expression. Studies using transgenic mice that overexpress MTs or MT null mice have revealed the role of MT in the protection of cells against numerous tissue-damaging agents such as reactive oxygen species. The primary physiological function of these proteins, however, remains an enigma. Considerable advances have been made in the identification of the cis-acting elements that are involved in the constitutive and induced expression of MT-I and MT-II. By contrast, only one key trans-activating factor, namely MTF-1, has been extensively characterized. Studies on the epigenetic silencing of MT-I and MT-II by promoter hypermethylation in some cancer cells have posed interesting questions concerning the functional relevance of MT gene silencing, the molecular mechanisms of MT suppression in these cells, particularly chromatin modifications, and the characteristics of the repressors.

Bremelanotide: New Drug Approved for Treating Hypoactive Sexual Desire Disorder.

Objective: To review data regarding bremelanotide, a recently approved therapy for hypoactive sexual desire disorder (HSDD). Data Sources: Literature search of Medline, SCOPUS, and EMBASE was performed using the search terms bremelanotide, bremelanotide injection, Vyleesi, and melanocortin 4 receptor agonist between January 1, 1996, and December 15, 2019. Reference lists from included articles were also reviewed for pertinent citations. Study Selection/Data Extraction: We included phase 2 and 3 trials of bremelanotide. There were 2 reports of phase 3 trials and 2 reports of phase 2 trials. Additional information from supplementary analyses was also referenced. Data Synthesis: Bremelanotide demonstrates significant improvement in desire and a significant decrease in distress related to lack of desire. The most common adverse effects include nausea (39.9%), facial flushing (20.4%), and headache (11%). Relevance to Patient Care and Clinical Practice: Bremelanotide is the second Food and Drug Administration-approved medication for the treatment of HSDD. Bremelanotide's place in therapy is unknown, as the HSDD guidelines were last updated in 2017. Although the trials met statistical significance for change in sexual desire elements and distress related to sexual desire, the clinical benefit may only be modest. Conclusion: Bremelanotide is a subcutaneous injection that can be administered as needed approximately 45 minutes prior to sexual activity. Bremelanotide is safe and has limited drug-drug interactions, including no clinically significant interactions with ethanol. Prescribing guidelines recommend no more than 1 dose in 24 hours and no more than 8 doses per month. Individuals should discontinue use after 8 weeks without benefit.

Disruption of Gpr45 causes reduced hypothalamic POMC expression and obesity.

A rise in the occurrence of obesity has driven exploration of its underlying genetic basis and potential targets for intervention. GWAS studies have identified obesity susceptibility pathways involving several neuropeptides that control energy homeostasis, suggesting that variations in the genes that regulate food intake and energy expenditure may contribute to obesity. In this study, we identified 5 additional obesity loci, including a neuronal orphan GPCR called Gpr45, in a forward genetic screen of mutant mice generated by piggyBac insertional mutagenesis. Disruption of Gpr45 led to increased adiposity at the time of weaning and increases in body mass, fat content, glucose intolerance, and hepatic steatosis with advancing age. Mice with disruptions in Gpr45 also displayed a reduction in expression of the metabolic regulator POMC and less energy expenditure prior to the onset of obesity. Mechanistically, we determined that GPR45 regulates POMC expression via the JAK/STAT pathway in a cell-autonomous manner. Consistent with this finding, intraventricular administration of melanotan-2, an analog of the POMC derivative α-MSH, suppressed adult obesity in Gpr45 mutants. These results reveal that GPR45 is a regulator of POMC signaling and energy expenditure, which suggests that it may be a potential intervention target to combat obesity.

Re-Analyzing Phase III Bremelanotide Trials for "Hypoactive Sexual Desire Disorder" in Women.

Kingsberg et al. described results from two 24-week Phase III trials of bremelanotide for treating hypoactive sexual desire disorder (HSDD) in women. 72.72% of protocol-listed outcomes were not reported by Kingsberg et al., who provided results of 15 secondary measures which were not listed in the study protocols. None of their efficacy outcomes were reported in line with CONSORT data reporting standards and no secondary outcome had a stated rationale or cited evidence of validity. My meta-analysis of the trials' data, based on the FDA New Drug Application, found similar results to Kingsberg et al. However, Kingsberg et al. did not report that a) adverse event-induced study discontinuation was substantially higher on bremelanotide: OR = 11.98, 95% CI = 3.74-38.37, NNH: 6 or b) participants preferred placebo, measured by the combination of both 1) completing a clinical trial and 2) electing to participate in the follow-up open-label study (OR = 0.30, 95% CI = .24-.38, NNH: 4). Bremelanotide's modest benefits on incompletely reported post-hoc measures of questionable validity in combination with participants substantially preferring to take placebo suggest that the drug is generally not useful. Kingsberg et al.'s data reporting and measurement practices were incomplete and lacked transparency.

[Metallothionein '96].

Metallothionein (MT) has been considered to play important roles in metal homeostasis and also in protecting against metal toxicities. There are four MT isoforms in mammalian cells. Recent studies using MT-I and -II genes knockout mice demonstrated that MT-I and -II are mainly involved in the protection against metal toxicities, oxidative stresses, and apoptosis. The expression of MT-II gene by zinc is regulated through activation of the zinc regulatory factor (ZRF). MT-III, a brain-specific isoform, plays a role in preventing neuronal sprouting and in the repair after brain damage.

Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials.

To evaluate the safety and efficacy of bremelanotide for the treatment of premenopausal women with hypoactive sexual desire disorder. Two identical phase 3, randomized, double-blind, placebo-controlled, multicenter clinical trials (RECONNECT) evaluated the safety and efficacy of bremelanotide 1.75 mg administered subcutaneously as needed in premenopausal women with hypoactive sexual desire disorder. Patients were randomized 1:1 to 24 weeks of treatment with bremelanotide or placebo. Sample size was estimated based on simulations from key endpoints in patients with hypoactive sexual desire disorder from a prior trial. Coprimary efficacy endpoints were change from baseline to end-of-study in the Female Sexual Function Index-desire domain score and Female Sexual Distress Scale-Desire/Arousal/Orgasm item 13. Study 301 began on January 7, 2015, and concluded on July 26, 2016. Study 302 began on January 28, 2015, and concluded on August 4, 2016. Of the 1,267 women randomized, 1,247 and 1,202 were in the safety and efficacy (modified intent-to-treat) populations, respectively. Most participants were white (85.6%), from U.S. sites (96.6%), and had a mean age of 39 years. From baseline to end-of-study, women taking bremelanotide had statistically significant increases in sexual desire (study 301: 0.30, P<.001; study 302: 0.42, P<.001; integrated studies 0.35, P<.001) and statistically significant reductions in distress related to low sexual desire (study 301: -0.37, P<.001; study 302: -0.29, P=.005; integrated studies -0.33, P<.001) compared with placebo. Patients taking bremelanotide experienced more nausea, flushing, and headache (10% or more in both studies) compared with placebo. Both studies demonstrated that bremelanotide significantly improved sexual desire and related distress in premenopausal women with hypoactive sexual desire disorder. The safety profile was favorable. Most treatment-emergent adverse events were related to tolerability and the majority were mild or moderate in intensity. ClinicalTrials.gov, NCT02333071 (study 301) and NCT02338960 (study 302). Palatin Technologies, Inc., and AMAG Pharmaceuticals, Inc.

Novel Pharmacologic Treatments of Female Sexual Dysfunction.

This review evaluates pharmacologic treatments for female sexual dysfunction (FSD), focusing on hypoactive sexual desire disorder (HSDD). We provide clinically relevant applications for Food and Drug Administration (FDA)-approved medications (flibanserin and bremelanotide) and investigational therapies (Lorexys and testosterone combinations). Detailed study outcomes, safety profiles, and clinical strategies guide clinicians in appropriate diagnosis, patient selection, expectation setting, side effect management, and patient education, improving treatment outcomes and patient satisfaction.

Melanocortins in the treatment of male and female sexual dysfunction.

Melanocortinergic agents are currently being investigated for a possible therapeutic role in male and female sexual dysfunction. These investigations were sparked by findings that systemic administration of a synthetic analog of alpha-MSH, MT-II, causes penile erections in a variety of species, including humans. Several other melanocortinergic agents including HP-228, THIQ, and bremelanotide (PT-141) have since been shown to have erectogenic properties thought to be due to binding to melanocortin receptors in the central nervous system, particularly the hypothalamus. Bremelanotide, a nasally administered synthetic peptide, is the only melanocortinergic agent that has been clinically studied in both males and females. Data from Phase II clinical trials of bremelanotide support the use of melanocortin-based therapy for erectile dysfunction. Studies using animal models have demonstrated that pre-copulatory behaviors in female rats analogous to sexual arousal are evoked, and preliminary clinical data also suggest a role in promoting sexual desire and arousal in women. Based on bremelanotide clinical experience, administration of a melanocortin agonist is well tolerated and not associated the hypotension observed with phosphodiesterase-5 inhibitors currently used to treat erectile dysfunction. This review discusses investigations of melanocortin agonists for the treatment of sexual dysfunction with emphasis on proposed sites and mechanisms of action in the central nervous system that appear to be involved in melanocortinergic modulation of sexual function. Current research validates use of melanocortinergic agents for the treatment of both male and female sexual dysfunction.

Melanotan-II reverses memory impairment induced by a short-term HF diet.

A high-fat (HF) diet has been shown to increase the risk of neurological impairments and neurodegenerative disorders. The melanotropins used in this study have been associated with diet-related disorders; however, there is an absence of studies on their effect on diet-induced neurobehavioral conditions. Here, we investigated the possible relationship among diet, Melanotan-II (MT-II) targeting melanotropin receptors, and the behavior of zebrafish (Danio rerio). Surprisingly, even a short-term HF diet lasting for &#x223c;&#xa0;1&#xa0;% of the zebrafish's life had a strong developmental effect. Zebrafish fed the HF diet showed an impairment in recognition memory, elevated anxiety levels, and reduced exploratory propensity after just three weeks compared to zebrafish fed the control diet. These HF diet-induced abnormalities were reversed by MT-II. Animals fed a HF diet and treated with MT-II demonstrated recognition memory, anxiety, and exploratory behavior similar to the control group. This study provides evidence that even a short-term HF diet has an impact on memory and emotions and is the first study to show that MT-II reverses these changes.

Medical Treatment of Female Sexual Dysfunction.

Female sexual dysfunction (FSD) comprises multiple overlapping sexual disorders with a multifaceted cause within the frame of the biopsychosocial model. Health care providers can screen for FSD according to their level of expertise and deliver at least basic counseling before eventually referring to sexual medicine specialists for specific care. The therapeutic algorithm comprises a multidisciplinary approach, including pharmacologic and nonpharmacologic management. Flibanserin and bremelanotide are psychoactive agents indicated for the treatment of generalized acquired hypoactive sexual desire disorder (HSDD) in premenopausal women, whereas transdermal testosterone is effective on HSDD in postmenopausal women. Menopause hormone therapy (systemic and local) is the mainstay for individualized management of women at midlife.

LC-HRMS characterization of the skin pigmentation and sexual enhancers melanotan II and bremelanotide sold on the black market of performance and image enhancing drugs.

The spread of performance and image enhancing drugs (PIEDs) often requires forensic toxicology laboratories to identify unknown compounds without reference standards. We characterized the PIEDs melanotan II and bremelanotide, not legally marketed, in eight unknown samples confiscated by police together with anabolic steroids, hormone modulators, sexual enhancers and stimulants, intended for the black market of bodybuilders, using liquid chromatography-high resolution/high accuracy Orbitrap mass spectrometry (LC-HRMS). The characterization was carried out by the accurate mass measurements of MH+ ionic species, the study of their isotopic patterns and the associated relative isotopic abundance (RIA) values, as well as the accurate mass measurements of collision-induced product ions obtained in fragmentation experiments. LC-HRMS confirmed itself as a powerful analytical tool to elucidate the elemental composition and structural characteristics of unknown compounds.

Pharmacotherapy for Sexual Dysfunction in Women.

This review article discusses the controversy in the DSM-5 conceptualization and diagnostic criteria for female sexual dysfunction (FSD). An overview of recent studies on available treatments for hypoactive sexual desire disorder (HSDD), female sexual arousal disorder (FSAD), and genitopelvic pain/penetration disorder (GPPD) is provided. Include delineation of the process of care for pre- and postmenopausal women with HSDD; release of global position statement on testosterone therapy in women; updates on efficacy and safety of vaginal estrogen for genitourinary syndrome of menopause and bremelanotide for HSDD; removal of flibanserin alcohol REMS; and development of new technology to enhance bioavailability and brain delivery of treatments. The DSM-5 revision combining HSDD and FSAD into one diagnostic category is a less accurate characterization of these separate disorders and may hinder access to demonstrated effective treatments for the women with these conditions. There are a wide range of pharmacological, other physiological, and psychological treatment options available for women with FSD, which can be offered based on their specific symptoms, potential benefits/risks, and preferences.

Prespecified and Integrated Subgroup Analyses from the RECONNECT Phase 3 Studies of Bremelanotide.

Background: Hypoactive sexual desire disorder (HSDD), the most prevalent female sexual dysfunction, is characterized as persistent diminished desire for sexual activity accompanied by distress. The efficacy and safety of bremelanotide, a melanocortin receptor agonist approved by the U.S. Food and Drug Administration for treatment of acquired generalized HSDD in premenopausal women, were established in the phase 3 RECONNECT studies, two identically designed double-blind randomized placebo-controlled studies with an optional 52-week open-label extension. This report investigates efficacy of bremelanotide versus placebo according to prespecified subgroups (age, weight, body mass index [BMI], and bioavailable testosterone) in the RECONNECT studies. Materials and Methods: Patients self-administered bremelanotide 1.75&#x2009;mg or placebo subcutaneously using an autoinjector, as needed, before sexual activity for 24 weeks. Efficacy was assessed using change from baseline to end-of-study for Female Sexual Function Index desire domain and Female Sexual Distress Scale-Desire/Arousal/Orgasm Item 13 for bremelanotide versus placebo. Results: Among 1202 patients included in the integrated and subgroup analyses, bremelanotide achieved statistically significant improvements in measures of increased desire and decreased distress associated with low desire across all age, weight, and BMI subgroups, and all baseline bioavailable testosterone quartiles, with few exceptions. Bremelanotide was further associated with statistically significant increases in reported sexual desire (p&#x2009;<&#x2009;0.05) in patients not taking hormonal contraceptives, and with a numerical advantage in those taking hormonal contraceptives. Patients treated with bremelanotide experienced decreased distress compared with those in the placebo group at levels of statistical significance (p&#x2009;<&#x2009;0.05) regardless of hormonal contraceptive use. Statistically significant improvements were observed in the presence or absence of decreased arousal, and regardless of HSDD duration. Conclusions: Bremelanotide was associated with statistically significant improvements in sexual desire and reduced distress across several prespecified subgroups, with few exceptions.

5-Hydroxypyrroloindoline Affords Tryptathionine and 2,2'-bis-Indole Peptide Staples: Application to Melanotan-II.

With peptides increasingly favored as drugs, natural product motifs, namely the tryptathionine staple, found in amatoxins and phallotoxins, and the 2,2'-bis-indole found in staurosporine represent unexplored staples for unnatural peptide macrocycles. We disclose the efficient condensation of a 5-hydroxypyrroloindoline with either a cysteine-thiol or a tryptophan-indole to form a tryptathionine or 2-2'-bis-indole staple. Judicious use of protecting groups provides for chemoselective stapling using &#x3b1;-MSH, which provides a basis for investigating both chemoselectivity and affinity. Both classes of stapled peptides show nanomolar Ki's, with one showing a sub-nanomolar Ki value.

Metallothionein (MT) -I and MT-II expression are induced and cause zinc sequestration in the liver after brain injury.

Experiments with transgenic over-expressing, and null mutant mice have determined that metallothionein-I and -II (MT-I/II) are protective after brain injury. MT-I/II is primarily a zinc-binding protein and it is not known how it provides neuroprotection to the injured brain or where MT-I/II acts to have its effects. MT-I/II is often expressed in the liver under stressful conditions but to date, measurement of MT-I/II expression after brain injury has focused primarily on the injured brain itself. In the present study we measured MT-I/II expression in the liver of mice after cryolesion brain injury by quantitative reverse-transcriptase PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) with the UC1MT antibody. Displacement curves constructed using MT-I/II knockout (MT-I/II(-/-)) mouse tissues were used to validate the ELISA. Hepatic MT-I and MT-II mRNA levels were significantly increased within 24 hours of brain injury but hepatic MT-I/II protein levels were not significantly increased until 3 days post injury (DPI) and were maximal at the end of the experimental period, 7 DPI. Hepatic zinc content was measured by atomic absorption spectroscopy and was found to decrease at 1 and 3 DPI but returned to normal by 7DPI. Zinc in the livers of MT-I/II(-/-) mice did not show a return to normal at 7 DPI which suggests that after brain injury, MT-I/II is responsible for sequestering elevated levels of zinc to the liver. MT-I/II is up-regulated in the liver after brain injury and modulates the amount of zinc that is sequestered to the liver.

Induction of metallothionein by stress and its molecular mechanisms.

This article describes the effect of restraint stress or social reorganization stress on the induction of metallothionein (MT) in the liver, heart, lung, and spleen. Both MT-I and MT-II mRNA were elevated as much as 30-fold following just 12 h (one cycle) of restraint stress. The amount of MT protein also increased following stress. The MT induction was the highest in the liver, followed by the lung, heart, and spleen. MT-I induction was also observed in the fore, mid, and hind regions of the brain whereas the brain-specific MT-III gene was not activated by stress. The increase in MT mRNA correlated well with the rise in stress-induced serum corticosterone. The induction occurred at the transcriptional level and was mediated essentially by the activation of glucocorticoid receptor. The MT mRNA returned to the control level after nine cycles of stress. Exposure of these habituated mice to a different type of stress (treatment with heavy metals such as cadmium or zinc sulfate) led to further MT induction. Because heavy metals induced MT via activation of the factor MTF-1, distinct molecular mechanisms should be responsible for the activation of MT promoter by different inducers.

Pharmacologic therapeutic options for sexual dysfunction.

Sexual problems are reported by up to 45% of individuals assigned female at birth. Although sexual function is a complex biopsychosocial construct, there are a number of pharmacologic treatment options aimed at addressing the changing vaginal hormonal milieu in postmenopausal individuals and moderating the excitatory and inhibitory aspects of the central nervous system in those with hypoactive sexual desire disorder. The last decade has seen an increase in the number and type of pharmacologic treatment options for dysfunction primarily associated with menopause and hypoactive sexual desire disorder. Recent publications and systematic reviews have strengthened the safety data of existing FDA-approved medications as well as off-label therapies. Pharmacologic treatment with local estrogen and testosterone replacement in postmenopausal individuals and with centrally-acting therapies such as flibanserin, bremelanotide, and testosterone in premenopausal individuals assigned female at birth are safe and can be used to improve sexual desire and sexual satisfaction.

Effect of bremelanotide on body weight of obese women: Data from two phase 1 randomized controlled trials.

The melanocortin 4 receptor (MC4R) plays a central role in appetite regulation, and agonistic activity at this receptor promotes satiety. Results from two randomized controlled clinical trials examine the effects of bremelanotide's agonism at MC4R on caloric intake and body weight. Premenopausal women with a body mass index >30&#x2009;kg/m2 were studied in two phase 1, single-centre, randomized, double-blind, placebo-controlled trials. Study A matched subjects 1:1 to receive subcutaneous placebo or bremelanotide three times daily for days 1-15. Study B was a crossover trial with six distinct treatment sequences consisting of three 4-day treatment periods, investigating once-a-day and twice-a-day exposure to bremelanotide versus placebo. Subjects received one of the three treatments twice-daily during each period: 0&#xa0;mg/0&#xa0;mg, 2.5&#xa0;mg/0&#xa0;mg or 2.5&#xa0;mg/2.0&#xa0;mg bremelanotide. Body weight and food intake were recorded in detail daily. Adverse events were recorded throughout both studies. In Study A, 27 of 30 bremelanotide subjects (90.0%) completed the trial and exhibited a significantly greater reduction in body weight after 16&#x2009;days versus placebo [least squares mean difference (95% CI), -1.3 (-1.9 to -0.8) kg; p&#x2009;<&#x2009;.0001]. Mean caloric intake in bremelanotide subjects was decreased versus placebo, with a magnitude of reduction of approximately 400&#x2009;kcal/day throughout Study A (p&#x2009;<&#x2009;.01). In Study B, 15 of 27 subjects (55.6%) completed all three phases. Significantly greater reduction of mean body weight occurred in twice-daily bremelanotide subjects versus placebo (1.7 vs. 0.9&#xa0;kg, respectively, p&#x2009;<&#x2009;.001). Total caloric intake reduction was significantly greater in the bremelanotide groups versus placebo (mean difference range: 398-469&#x2009;kcal; p&#x2009;<&#x2009;.0001). Agonist activity at the MC4R may aid in reducing caloric intake and weight loss in obese women.

A glimpse into the underground market of melanotan.

Melanotan-I and melanotan-II are alpha-melanocyte stimulating hormone (a-MSH) analogues that can be purchased illicitly online with relative ease and are injected subcutaneously to stimulate a tan. Little is known about the use of these unregulated substances. An observational survey was posted to an online forum in which participants share their experiences using melanotan-I or melanotan-II. Users were asked to complete this voluntary, anonymous survey, which had questions focusing on motivation and hesitation for and against using melanotan, difficulty in acquiring it, and plans for continuing to use melanotan in the future.

Melanotan II: a possible cause of renal infarction: review of the literature and case report.

Renal infarction is an uncommon condition resulting from an acute disruption of renal blood flow and it is potentially life-threatening disease. The cause and outcome of renal infarction is not well established and is frequently misdiagnosed or diagnosed late. Melanotan II is a non-selective melanocortin-receptor agonist and its effect on humans is an increasing of skin pigmentation, producing of spontaneous penile erection and sexual stimulation. Melanotan II inducing rhabdomyolysis and renal failure have been described previously. We present a review of Melanotan II and the possible effects of this drug on the kidneys by including a case of a renal infarction most likely attributed to Melanotan II. In the mechanism of renal injury with Melanotan II, thrombotic pharmacological influence and possible direct toxic effect on renal parenchyma must be considered.

The neurobiology of bremelanotide for the treatment of hypoactive sexual desire disorder in premenopausal women.

Hypoactive sexual desire disorder (HSDD) is a common female sexual dysfunction and is estimated to affect approximately 10% of women in the United States. It has been suggested that HSDD is associated with an imbalance of hormone and neurotransmitter levels in the brain, resulting in decreased excitation, increased inhibition, or a combination of both. Evidence suggests neurotransmitters, including dopamine (DA), norepinephrine, and serotonin, as well as hormones such as estradiol and testosterone, contribute to female sexual desire and response. Current treatments for HSDD include psychotherapy, and two US Food and Drug Administration-approved medications for premenopausal women: flibanserin, a serotonin mixed agonist and antagonist, and bremelanotide, a melanocortin receptor (MCR) agonist. Melanocortins are endogenous neuropeptides associated with the excitatory pathway of the female sexual response system. MCRs are found throughout the body, including the brain. Bremelanotide is an MCR agonist that nonselectively activates several of the receptor subtypes, of which subtype 4 (MC4R) is the most relevant at therapeutic doses. MC4R is predominantly expressed in the medial preoptic area (mPOA) of the hypothalamus in the brain, and is important for female sexual function. Animal studies suggest that bremelanotide may affect female sexual desire by activating presynaptic MC4Rs on neurons in the mPOA of the hypothalamus, leading to increased release of DA, an excitatory neurotransmitter that increases sexual desire. This review presents what is known about the mechanism of action of bremelanotide in the context of treating HSDD.

An evaluation of bremelanotide injection for the treatment of hypoactive sexual desire disorder.

Female sexual response implies a deep intertwining between psychosocial and neurobiological mediators. Regulation of central melanocortin signaling may enhance sexual desire. In premenopausal women with hypoactive sexual desire disorder (HSDD), melanocortin receptor agonist bremelanotide (Vyleesi) has been hypothesized to trigger excitatory brain pathways. Hereby we summarize bremelanotide's proposed mechanism of action, pharmacokinetics, efficacy and safety data derived from clinical trials. A literature search of peer-reviewed publications on the current evidence on the pharmacotherapy with bremelanotide was performed using the PubMed database. Bremelanotide appears to be moderately safe and well-tolerated; the most common adverse reaction is nausea (40%). Although data from clinical trials demonstrated a significant change in validated questionnaires, the overall clinical benefit appears to be modest. However, these results should be interpreted in the light of the dramatic challenges in conducting well-designed clinical trials for female sexual dysfunction, due to the significant placebo effect of pharmacotherapy, and the frequent use of outcome measures that are likely to be highly susceptible to expectation biases, such as long periods of recall of sexual and emotional response.

The functional significance of brain metallothioneins.

Metallothioneins (MTs) are ubiquitous low molecular weight proteins characterized by their abundant content of cysteines. Two MT isoforms, MT-I and MT-II, are expressed coordinately in all mammalian tissues. In the CNS, MT-I and MT-II are conspicuously absent from neuronal populations, yet abundant in fibrous and protoplasmic astrocytes. A newly identified brain-specific MT gene, MT-III, is predominantly expressed in zinc-containing neurons of the hippocampus and absent from glial elements. MTs have been implicated as regulator molecules in gene expression, homeostatic control of cellular metabolism of metals, and cellular adaptation to stress. MTs store and release essential metals, such as zinc and copper, maintaining the low intracellular concentration of free essential metals. Thus, MTs fulfill a regulatory capacity and influence transcription, replication, protein synthesis, metabolism, as well as other zinc-dependent biological processes. Because MT-III is particularly abundant in zinc-containing neurons of the hippocampus, it is likely to play an important role in neuromodulation by zinc-containing neurons and to act as a sink for free zinc. It may also play an etiologic role in various pathophysiological conditions associated with increased extracellular zinc. Studies demonstrating that MT-III prevents neuronal sprouting in vitro, appears to be down-regulated in Alzheimer's disease, and that MT-III "knockout" mice appear highly sensitive to kainateinduced seizures have focused growing attention on the etiologic role of MT-III in neurodegeneration.-Aschner, M. The functional significance of brain metallothioneins.

Melanoma associated with the use of melanotan-II.

Unlicensed use of melanotan-II (MT-II) to promote skin pigmentation has become prevalent amongst young people attending fitness centres. We present a case where the melanocyte stimulation of MT-II in combination with the use of sun tanning beds coincided with cutaneous melanoma. A 20-year-old woman with Fitzpatrick skin type II was referred to a dermatology clinic. Clinical examination revealed a suspicious black melanocytic lesion in her left gluteal region. Furthermore, her skin was universally intensely pigmented. The melanocytic lesion was excised, and histology confirmed the diagnosis of melanoma. Three months prior to the excision the patient had conducted a 3- to 4-week course of self-injections with MT-II, intending an augmentation of sunbed tanning. This observation brings attention to the potential risks related to the use of the cyclic &#x3b1;-melanocyte-stimulating hormone analogue MT-II. There are several hazardous aspects of the possible widespread use of MT-II. As the drug is unlicensed and incompletely tested, the extent and types of adverse effects are unknown. Clinicians are advised to be aware of the problem, and counsel their at-risk patients regarding the potential hazards related to the use of MT-II.

A review of metallothionein isoforms and their role in pathophysiology.

The Metallothionein (MT) is a protein which has several interesting biological effects and has been demonstrated increase focus on the role of MT in various biological systems in the past three decades. The studies on the role of MT were limited with few areas like apoptosis and antioxidants in selected organs even fifty years after its discovery. Now acknowledge the exploration of various isoforms of MT such as MT-I, MT-II, MT-III and MT-IV and other isoforms in various biological systems.Strong evidence exists that MT modulates complex diseases and the immune system in the body but the primary function of MT still remains unknown. This review's main objective is to explore the capability to specifically manipulate MT levels in cells and in animals to provide answers regarding how MT could impact those complex disease scenarios.The experimental result mentioned in this review related among MT, zinc, cadmium, diabetic, heart disease, bone retardation, neuro toxicity, kidney dysfunction, cancer, and brain suggest novel method for exploration and contribute significantly to the growing scientist to research further in this field.

Human metallothionein MT-I and MT-II processed genes.

Two intronless pseudogenes, corresponding to the human metallothionein MT-I and MT-II processed genes, have been isolated from a human genomic library. MT-I processed gene has accumulated a number of mutations including a nonsense mutation giving rise to a termination codon at amino acid position 21, and a single base deletion at amino acid position 47 causing a shift in the reading frame. MT-II processed gene is a full-length perfect copy of its corresponding mRNA except for a few mutations. Most of the mutations in MT-II processed gene are silent except that the amino acid glycine (GGT) at position 10 is changed to serine (AGT) due to a transition. Both MT-I and MT-II processed genes possess poly(A) sequences of 21 and 17 nucleotides, respectively, 3' to the consensus AATAAA sequence. While these genes are quite similar in their sequences at the 3'-untranslated region, they show less than 50% homology in the 5'-untranslated sequences. Two direct repeats of 16 and 18 nucleotides in length define the limits of the MT-I and MT-II processed genes, respectively, and have been confirmed by S1 nuclease mapping analysis. In both MT-I and MT-II processed genes these direct repeats towards the 5' end of the gene start with an AhaIII (TTTAAA) restriction site. Our studies suggest that these direct repeats are the results of the insertion site duplication.

Bremelanotide: the female Viagra?

Melanotan II User Experience: A Qualitative Study of Online Discussion Forums.

Melanotan II (MT II) is a synthetic analogue of &#x3b1;-melanocyte-stimulating hormone that, via interaction with the melanocortin 1 receptor, induces skin hyperpigmentation. The unregulated acquisition of MT II injections via the internet and other outlets has become popular over the last decades in order to exploit its properties for use as a tanning agent. Due to the covert nature of MT II use, it is difficult to assess the extent of its use among the general population and to characterise any associated side effects. The aim of this study was to qualitatively examine MT II use, as portrayed on online forums, and to explore the motivations for its use and side effect profile. Data were extracted retrospectively from UK and Ireland online chatrooms and forums from January 2016 to October 2017. Inclusion criteria were active MT II chatrooms and forums considered to be within the public domain. An inductive thematic analysis identified themes within discussion threads. A total of 623 discussion entries were extracted; 205 participants contributed to these entries. Emergent themes included motivation for MT II use, misinformation in the context of using an unregulated product, product preparation and administration, dosing regimens, sunbed use, side effects and concerning practices associated with MT II use. Motivations for MT II use included the pursuit of a tanned appearance, often in anticipation of sun holidays and fitness/body building competitions. Clinicians should be aware not only of the potential risks in relation to pigmented skin lesions, but also remain cognisant of the other medical hazards associated with the use of this substance, namely transmission of infectious diseases, use of potentially contaminated products, polypharmacy, and sunbed exposure.

Development of Ligand-Drug Conjugates Targeting Melanoma through the Overexpressed Melanocortin 1 Receptor.

Melanoma is a lethal form of skin cancer. Despite recent breakthroughs of BRAF-V600E and PD-1 inhibitors showing remarkable clinical responses, melanoma can eventually survive these targeted therapies and become resistant. To solve the drug resistance issue, we designed and synthesized ligand-drug conjugates that couple cytotoxic drugs, which have a low cancer resistance issue, with the melanocortin 1 receptor (MC1R) agonist melanotan-II (MT-II), which provides specificity to MC1R-overexpressing melanoma. The drug-MT-II conjugates maintain strong binding interactions to MC1R and induce selective drug delivery to A375 melanoma cells through its MT-II moiety in vitro. Furthermore, using camptothecin as the cytotoxic drug, camptothecin-MT-II (compound 1) can effectively inhibit A375 melanoma cell growth with an IC50 of 16 nM. By providing selectivity to melanoma cells through its MT-II moiety, this approach of drug-MT-II conjugates enables us to have many more options for cytotoxic drug selection, which can be the key to solving the cancer resistant problem for melanoma.

Metallothioneins are multipurpose neuroprotectants during brain pathology.

Metallothioneins (MTs) constitute a family of cysteine-rich metalloproteins involved in cytoprotection during pathology. In mammals there are four isoforms (MT-I - IV), of which MT-I and -II (MT-I + II) are the best characterized MT proteins in the brain. Accumulating studies have demonstrated MT-I + II as multipurpose factors important for host defense responses, immunoregulation, cell survival and brain repair. This review will focus on expression and roles of MT-I + II in the disordered brain. Initially, studies of genetically modified mice with MT-I + II deficiency or endogenous MT-I overexpression demonstrated the importance of MT-I + II for coping with brain pathology. In addition, exogenous MT-I or MT-II injected intraperitoneally is able to promote similar effects as those of endogenous MT-I + II, which indicates that MT-I + II have both extra- and intracellular actions. In injured brain, MT-I + II inhibit macrophages, T lymphocytes and their formation of interleukins, tumor necrosis factor-alpha, matrix metalloproteinases, and reactive oxygen species. In addition, MT-I + II enhance cell cycle progression, mitosis and cell survival, while neuronal apoptosis is inhibited. The precise mechanisms downstream of MT-I + II have not been fully established, but convincing data show that MT-I + II are essential for coping with neuropathology and for brain recovery. As MT-I and/or MT-II compounds are well tolerated, they may provide a potential therapy for a range of brain disorders.

Protective role of metallothionein in chemical and radiation carcinogenesis.

Metallothionein (MT) is a low molecular weight metal-binding protein induced by endogenous and exogenous stimuli such as cytokines and heavy metals. In 1993 and 1994, two research groups (Choo et al. and Palmiter et al., respectively) produced MT-I/II double-knockout mice (MT-I/II null mice) with null mutations of the MT-I and MT-II genes. Subsequently, MT-I/II null mice have been used to clarify the biological function, physiological role, and pathophysiological relevance of MT by many research groups. Recent studies using MT-I/II null mice to investigate the role of MT in metal toxicity and distribution, oxidative stress, and some disease were reviewed. In addition, several research groups including our laboratory have reported that MT-I/II null mice are highly susceptible to several carcinogenesis caused by 7,12-dimethylbenz[a]anthracene, X-ray, benzo[a]pyrene, N-butyl-N-(4-hydroxybutyl) nitrosamine, lead, and cisplatin. These results suggest that MT is an important protective factor against not only metal toxicity and oxidative stress but also chemical and radiation carcinogenesis. In this review, we present the findings of MT-I/II null mice with regard to the protective role of MT in carcinogenesis and mutagenesis caused by chemical agents and X-ray.

Barbie drug identification: Not a child's play.

Various samples-including two vials with a pharmaceutical appearance-were submitted to the laboratory for identification. The aim of this work was to describe the unique characteristics observed during the analysis of the powder contained in the vial. Samples were submitted to HPLC-DAD, UHPLC-TOF-MS, and/or UPLC-MS-MS analysis. The majority of the samples were easily identified as standard drugs of abuse. The main difficulty lay in identifying the powder in the vials. No match was found in the library through HPLC-DAD analysis. Fortunately, the vials were labeled as "Melanotan II", although the UV spectrum was not available. Mass spectrometric analysis of melanotan II was challenging, as it is a small peptide with a molecular weight of 1024&#x2009;Da, which is significantly heavier than classical drugs that the laboratory usually handles. As a result, mass spectrometer's parameters can be limited to detect masses up to 1000&#x2009;Da. Additionally, melanotan II is multi-charged which is also unusual for compounds typically targeted in our daily work. Finally, the reference standard allowed us to confirm the identification with both instruments, and determine the purity of 30%. Melanotan II is not approved on the market due to safety concerns. It is used illegally mainly for tanning, explaining its nickname "Barbie drug". To conclude, analysis of melanotan II was challenging as it is heavy and doubly charged. Moreover, its UV spectrum was initially not available in the literature. The difficulties faced by forensic scientists in detecting this drug may explain its popularity on the illicit market.