Drug Treatments for Women's Sexual Disorders

Journal of Sex Research, August, 2000 by Walter Everaerd, Ellen Laan

Smooth muscle contractions of the reproductive tract and contractions of striated muscles of the pelvic floor are supposed to be the cause of sensations of orgasm. Carmichael et al. (1987) hypothesized that oxytocin is involved in orgasmic muscle contractions, because of its classical function in smooth muscle contractions during parturition and for milk ejection. In women and men oxytocin release was measured before, during, and after orgasm in blood samples taken from the forearm. An anal probe allowed monitoring of EMG and blood-pulse amplitude changes. Subjects indicated the beginning and end of their subjective orgasm. Data of the anal probe and the subjective report proved to be closely matched. Oxytocin levels increased throughout self-stimulation and peaked during orgasm, followed by a decrease. Mean plasma oxytocin level in women was significantly higher than in men. Recently, Blaicher et al. (1999) corroborated the oxytocin release for women. They provide oxytocin values for baseline, 1 minute after orgasm, and 5 minutes after orgasm. An increase in oxytocin from baseline to 1 minute after orgasm occurs in all subjects, although with considerable between-subject variation. These results confirm the conclusion of Carmichael et al. (1987) that oxytocin plays an important role in the physiology of sexual responses by facilitating contractions of the uterus and the vagina in women.

The bonding features of oxytocin have been explored in a study that investigated changes in plasma oxytocin as a consequence of emotions and interpersonal distress in women (Turner, Altemus, Enos, Cooper, & McGuinness, 1999). Oxytocin changes were provoked in subjects by "soft Swedish massage of neck and shoulders'" (p. 101) and by induction of negative and positive emotions. Interpersonal variables were measured with questionnaires. Oxytocin was assessed using blood samples drawn from an indwelling catheter during experimental manipulations. The results indicate that changes in peripheral oxytocin are related to interpersonal characteristics. Although considerable individual differences were found, positive emotion, massage, and being in a current relationship tended to be associated with oxytocin increase. Negative emotion seemed to inhibit oxytocin.

On the basis of animal data vasopressin is suspected to have the same social bonding effects as oxytocin. Thus far, there are no reports about specific effects in women. Vasopressin is implicated in memory and emotion, and it has been used as a treatment for memory problems in older people. The sexual action of vasopressin is dependent on testosterone. One may speculate that it has a role in sexual fantasies, and consequently in sexual desire (Crenshaw & Goldberg, 1996).

Sex Steroids

Prosexual effects of sex steroids are discussed in relation to the normal menstrual cycle and during the postmenopause. It has proven to be difficult to establish the role of sex steroids in women. Most women experience an increase in their sexual functioning during puberty. They also experience considerable changes in hormone levels and in hormonal patterns in their reproductive and postmenopausal years. However, it has been difficult to relate serum levels of sex steroids to sexual functioning (Gooren, in press).