Sexual Function & Performance
12/08/2026
Sexual function involves a complex interaction between the central nervous system, reproductive hormones, vascular function and neuroendocrine signalling.
Research into peptides and related signalling molecules is investigating pathways involved in:
The evidence varies considerably between compounds. Some have been investigated in controlled human studies, while others remain primarily experimental.
Three peptides of particular research interest are bremelanotide (PT-141), kisspeptin and Melanotan II.
Bremelanotide, also known as PT-141, is a synthetic melanocortin-receptor agonist.
Research has investigated its effects on central pathways involved in sexual desire and arousal. The precise mechanism responsible for its clinical effects is not completely established.
The broader research pathway can be summarised as:
PT-141 → melanocortin-receptor signalling → central sexual-response pathways → changes in sexual desire and arousal
Bremelanotide has been evaluated in randomized clinical trials involving women with acquired, generalized hypoactive sexual desire disorder (HSDD).
The FDA-approved product, Vyleesi, is indicated for this specific condition in premenopausal women. It is not indicated for men or for enhancing sexual performance.
Earlier clinical research also investigated bremelanotide in men with erectile dysfunction, including men who had not responded adequately to sildenafil. These studies provide evidence of an erectogenic effect but did not establish bremelanotide as an approved treatment for male erectile dysfunction.
Kisspeptin is an endogenous neuropeptide involved in regulation of the reproductive endocrine system.
It acts through the KISS1 receptor (KISS1R) and is an important upstream regulator of gonadotropin-releasing hormone (GnRH).
The principal reproductive pathway can be summarised as:
Kisspeptin → KISS1R → GnRH signalling → LH / FSH → reproductive hormone regulation
Research suggests that kisspeptin may also have effects beyond reproductive hormone regulation, including activity within brain regions involved in sexual motivation and emotional processing.
Human studies have investigated kisspeptin in both men and women with low sexual desire.
In men with HSDD, a randomized controlled study reported changes in sexual brain processing, penile tumescence and measures of sexual desire during kisspeptin administration.
A separate randomized clinical study in women with HSDD found changes in brain responses to erotic and facial-attraction stimuli during kisspeptin administration.
These findings make kisspeptin an important experimental research pathway linking reproductive signalling with sexual motivation and brain activity.
However, kisspeptin remains investigational and has not been established as a standard treatment for sexual dysfunction.
Melanotan II is a synthetic analogue of α-melanocyte-stimulating hormone and acts on melanocortin receptors.
It attracted scientific interest because early research identified effects on sexual physiology in addition to its melanotropic activity.
The proposed pathway can be simplified as:
Melanotan II → melanocortin receptors → central sexual-response pathways → penile erection / sexual-response effects
Small controlled human studies investigated Melanotan II in men with erectile dysfunction.
One study involving men with psychogenic erectile dysfunction reported clinically apparent erections in most participants receiving Melanotan II.
Another controlled study investigated men with erectile dysfunction associated with organic risk factors and reported increased erectile responses and sexual desire following administration. Nausea and yawning were among the reported adverse effects.
These findings provide evidence for melanocortin involvement in sexual physiology, but they do not establish Melanotan II as an approved treatment for erectile dysfunction.
| Peptide | Primary pathway investigated | Research area | Evidence |
|---|---|---|---|
| PT-141 / Bremelanotide | Melanocortin-receptor signalling | Sexual desire, arousal & erectile physiology | Human clinical research |
| Kisspeptin | KISS1R / reproductive signalling | Sexual motivation, brain activity & reproductive hormones | Early human research |
| Melanotan II | Melanocortin-receptor signalling | Erectile physiology & sexual response | Small human studies |
Sexual function consists of several distinct biological outcomes.
Sexual desire refers primarily to motivation or interest in sexual activity.
Sexual arousal involves psychological and physiological responses to sexual stimuli.
Penile tumescence describes measurable changes in penile blood volume and size and is commonly used as an experimental measure of physiological sexual arousal.
Erectile function involves the ability to achieve and maintain sufficient penile rigidity for sexual activity and depends substantially on vascular, neurological and smooth-muscle mechanisms.
These outcomes are related but are not interchangeable.
For example, a compound that alters sexual desire does not necessarily demonstrate an improvement in erectile function. Similarly, an experimental increase in penile tumescence does not automatically establish an improvement in sexual satisfaction or real-world sexual function.
Peptide research in sexual function can broadly be divided into several biological areas.
Central neuroendocrine signalling investigates how molecules such as melanocortins and kisspeptin influence brain pathways associated with sexual motivation and behaviour.
Reproductive signalling examines pathways involving kisspeptin, GnRH, LH, FSH and sex hormones.
Vascular signalling is particularly important in erectile physiology, where nitric oxide, cyclic GMP and vascular smooth-muscle relaxation contribute to penile erection.
These mechanisms should not be treated as equivalent.
For comparison, established PDE5 inhibitors act primarily through the nitric oxide/cGMP pathway and have a substantially larger clinical evidence base for male erectile dysfunction. Current European guidelines recommend PDE5 inhibitors as first-line pharmacological treatment for erectile dysfunction.
The current research suggests that peptide signalling can influence sexual function through several different biological pathways.
PT-141 / bremelanotide has the most developed clinical evidence of the three compounds discussed here and has been evaluated in controlled trials for HSDD. Its approved indication is specific to premenopausal women with acquired, generalized HSDD.
Kisspeptin is primarily a reproductive neuropeptide, but controlled human studies have identified effects on sexual brain processing, sexual desire and physiological sexual arousal.
Melanotan II provides early human evidence supporting a role for melanocortin signalling in erectile physiology, but the available evidence comes from relatively small studies and does not establish an approved therapeutic use.
The evidence should therefore be interpreted according to the specific compound, biological pathway, study population and measured outcome.
The information presented on this page summarises published scientific and clinical research and is provided for educational purposes.
The inclusion of a compound does not constitute a recommendation for use, treatment, prevention or performance enhancement.
Evidence from laboratory, animal or early-stage human research does not establish that a compound is safe or effective for personal use.
The term “research peptide” describes an experimental or research context and does not imply regulatory approval, clinical efficacy, pharmaceutical quality or suitability for human use.
Bremelanotide is an FDA-approved prescription medicine for a specific indication in premenopausal women with acquired, generalized HSDD. It is not indicated for men or for enhancing sexual performance.
Kisspeptin and Melanotan II remain research areas rather than established treatments for sexual dysfunction.
For male erectile dysfunction, established therapies such as PDE5 inhibitors have a substantially larger clinical evidence base and are recommended as first-line pharmacological treatment in current European guidelines.
Research findings should therefore be considered in the context of the quality of evidence, regulatory status, study limitations and specific biological outcome being investigated.
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Clayton, A.H. et al. (2019) ‘Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials’, Obstetrics & Gynecology, 134(5), pp. 899–908. doi: 10.1097/AOG.0000000000003500.
Comninos, A.N. et al. (2017) ‘Kisspeptin modulates sexual and emotional brain processing in humans’, Journal of Clinical Investigation, 127(2), pp. 709–719. doi: 10.1172/JCI89519.
Mills, E.G. et al. (2023) ‘Effects of kisspeptin on sexual brain processing and penile tumescence in men with hypoactive sexual desire disorder: a randomized clinical trial’, JAMA Network Open, 6(2), e2254313. doi: 10.1001/jamanetworkopen.2022.54313.
Safarinejad, M.R. and Hosseini, S.Y. (2008) ‘Salvage of sildenafil failures with bremelanotide: a randomized, double-blind, placebo controlled study’, Journal of Urology, 179(3), pp. 1066–1071. doi: 10.1016/j.juro.2007.10.063.
Thurston, L. et al. (2022) ‘Effects of kisspeptin administration in women with hypoactive sexual desire disorder: a randomized clinical trial’, JAMA Network Open, 5(10), e2236131. doi: 10.1001/jamanetworkopen.2022.36131.
U.S. Food and Drug Administration (2020) Vyleesi (bremelanotide) prescribing information. Silver Spring, MD: U.S. Food and Drug Administration.
Wessells, H. et al. (2000) ‘Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction’, Urology, 56(1), pp. 127–132. doi: 10.1016/S0090-4295(00)00680-4.
Wessells, H., Levine, N., Hadley, M.E. et al. (2000) ‘Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II’, International Journal of Impotence Research, 12(Suppl. 4), pp. S74–S79. doi: 10.1038/sj.ijir.3900582.
