Evidence that serotonin affects female sexual functioning via peripheral mechanisms.

A review of the literature indicates that serotonin is active in several peripheral mechanisms that are likely to affect female sexual functioning. Serotonin has been found in several regions of the female genital tract in both animals and humans. In the central nervous system (CNS), serotonin acts primarily as a neurotransmitter, but in the periphery, serotonin acts primarily as a vasoconstrictor and vasodilator. Since, in the periphery, the principal component of sexual arousal is vasocongestion of the genital tissue, it is likely that serotonin participates in producing normal sexual arousal. In addition, serotonin administration produces contraction of the smooth muscles of the genito-urinary system and is found in nerves innervating the sexual organs. Taken together, this evidence suggests that peripheral serotonergic activity may be involved in the normal sexual response cycle. In addition, exogenous substances that alter serotonin activity, such as selective serotonin uptake inhibitors (SSRIs) and the atypical antipsychotics, can produce sexual dysfunction. It is possible that sexual side effects seen with these drugs may result, at least in part, from their action on peripheral mechanisms.