Preclinical effects of melanocortins in male sexual dysfunction

Abstract

The neurobiology of sexual behavior involves the interrelationships between sex steroids and neurotransmitters that result in both central nervous system (CNS) effects and effects in the genitalia. Tools such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) scanning can help determine what areas of the brain are activated under sexual stimulation. Our understanding of the role of various neurotransmitters, neurosteroids and other CNS-acting compounds is improving. The role of CNS-acting compounds such as dopamine agonists in the treatment of male sexual dysfunction is under active investigation. Melanocortins have CNS and peripheral roles in a wide variety of bodily functions. The melanocortin agonist bremelanotide appears to act in the CNS to promote erections in preclinical models, and may also stimulate behaviors that facilitate sexual activity beyond their erectogenic effects.

The role of ghrelin signalling for sexual behaviour in male mice

“…). In line are the data showing that the anorexigenic peptides leptin and melanocortins, such as alpha‐melanocyte‐stimulating hormone, inhibit mating behaviours in male rodents (for review see, Shadiack & Althof ; Schneider et al . ).…”

“…). Indeed, pharmacological studies show that an enhanced activity in dopaminergic systems facilitates sexual behaviour, whereas reduced dopaminergic activity attenuates sexual behaviour (for review, see Paredes & Agmo ; Shadiack & Althof ). The rewarding (Melis & Argiolas ) as well as motivational (Pfaus & Phillips ; van Furth, Wolterink & van Ree ) properties of sexual behaviour are mediated via increased accumbal dopamine levels.…”

“…). It has also been proposed that dopamine is involved in anticipatory rather than in consummatory motivational sexual responses (for review, see Shadiack & Althof ). However, there are also findings contradicting a role of accumbal dopamine for sexual behaviour in rodents (for review, see Paredes & Agmo ).…”

“…A role of dopamine outside the mesolimbic dopamine system cannot be excluded. Indeed, there are other dopamine projections, such as the tuberoinfundibular, the incertohypothalamic and the diencephalospinal, that might be of interest (for review, see Shadiack & Althof ).…”

Latent Structures of Male Sexual Functioning

“…According to Corona and colleagues [29], hypoactive sexual disorder in men could contribute to the pathogenesis of erectile dysfunction. However, although erectile response could sign the presence of desire, one can have erections without desire and vice‐versa [36]. In fact, sleep‐related erections, not only result from a different physiological process (as compared with the erectile response related to tactile and visual erotic stimuli during wakefulness), but apparently have also distinct purposes related to the prevention of cavernous fibrosis [37].…”