Relationships among cardiovascular, muscular, and oxytocin responses during human sexual activity.

To determine the psychophysiological correlates of hormonal response during sexual activity, systolic blood pressure (SBP), anal electromyography (EMG), and anal photoplethysmography (APG) were monitored continuously throughout testing in 13 women and 10 men. Each subject completed two or more tests of self-stimulation to 5 min beyond orgasm. Blood samples were obtained continuously for measurement of oxytocin (OT) levels. In both men and women, very high positive correlations were observed between the percentage change in levels from baseline through orgasm of: OT and SBP; OT and EMG intensity prior to and during orgasm; APG and EMG. The number of anal contractions and duration of orgasm were also highly correlated. Two patterns of orgasm were defined by the presence or absence of a quiescent period between orgasmic contractions. EMG and APG amplitudes correlated with the pattern of orgasm. Subjective orgasm intensity correlated significantly with increased levels of OT in multiorgasmic women only. The positive correlations between measures are consistent with a possible functional role for OT in human sexual response.

Effects of estrogen, androgen, and progestin on sexual psychophysiology and behavior in postmenopausal women.

To assess the contribution of gonadal steroids to sexual behavior in aging women, we conducted a 10-week, double-blind, hormone replacement study of 40 naturally menopausal women (mean age, 58.3 yr). Prospective measurements of basal and stimulated vaginal vasocongestion and daily self-reports of mood, physical symptoms, sexual behavior, and perceived sexual pleasure were collected. Daily treatments were either conjugated equine estrogen, i.e. Premarin (P; 0.625 mg), Premarin and medroxyprogesterone acetate, i.e. Provera (PP; 0.625 and 5 mg, respectively), Premarin and methyltestosterone (PT; 0.625 and 5 mg, respectively), or placebo (PL). Compared to placebo, hormone treatment had significantly reduced hot flashes in the P and PP groups by week 4 and in the PT group by week 5. Headaches were reduced in the P vs. PL group, only. Hormone treatment did not significantly alter mood ratings, sexual behaviors, or psychophysiologically measured sexual arousal. PT treatment significantly increased reports of pleasure from masturbation compared to the other three groups, underscoring the apparent contribution of androgens to self-stimulatory behavior. However, the data suggest that in these physically and sexually healthy women, gonadal steroids do not influence major components of sexual functioning, including arousal and a wide variety of sexual activity and experience.

Plasma oxytocin increases in the human sexual response.

The purpose of this study was to determine whether plasma oxytocin (OT) levels change during human sexual responses and, if so, to demonstrate the temporal pattern of change. Plasma OT levels were measured by RIA before, during, and after private self-stimulation to orgasm in normal men (n = 9) and women (n = 13). Blood samples were collected continuously through indwelling venous catheters. The subjects pressed a signal to indicate the start and finish of orgasm/ejaculation. Objective assessment of sexual arousal and orgasm was obtained by measuring blood-pulse amplitude and electromyographic activity, recorded continuously throughout testing from an anal device containing a photoplethysmograph and electromyograph electrodes connected to a polygraph located in an adjacent room. These measures allowed collection of data from men and women of changes in blood flow and muscle activity in the lower pelvic/pubic area. Plasma OT levels increased during sexual arousal in both women and men and were significantly higher during orgasm/ejaculation than during prior baseline testing. We suggest that the temporal pattern of secretion could be related to smooth muscle contractions of the reproductive system during orgasm.

Psychosocial characteristics of applicants evaluated for surgical gender reassignment.

Social, sexual, economic, familial, and psychological characteristics of 764 applicants for surgical gender reassignment, 479 males and 285 females, who completed the application questionnaire and were subsequently interviewed by the Gender Dysphoria Program in Palo Alto, California, are examined. All information except diagnosis was obtained from the applicants' responses to a standardized 100-item questionnaire. Diagnosis was determined by a psychiatrist after a 1 1/2-hour interview. A comparison of male applicants to female applicants indicated differences in five areas: (1) sexual history; (2) acting-out behavior or sociopathy; (3) work history; (4) strategies for physically passing in the desired gender, e.g., hormone therapy; and (5) diagnosis. Females had experienced more stable same-sex sexual relationships and fewer opposite-sex sexual relationships than the males had experienced. The females exhibited less acting-out behavior, indicated by few criminal convictions and little involvement in prostitution, compared to the male applicants. Twice as many males as females were unemployed and receiving welfare at the time of application. In addition, males used cosmetic surgery and hormone therapy more frequently to facilitate physically passing in the desired gender than did the females. The most frequent diagnosis for males was transvestitism, while for the females it was classic transsexualism.

The influence of age and cycling status on sexual arousability in women.

The effects of age and hormonal status on sexual response were quantitatively assessed by the use of a vaginal photoplethysmograph to measure changes in pulse amplitude in response to erotic film and fantasy. In young, regularly cycling women (mean age, 31 years) there were no significant differences in sexual response between the follicular, ovulatory, and luteal phases. The older premenopausal women (mean age, 51 years) showed responses not significantly different from those of the young cycling women. However, both the younger cycling women and older premenopausal women had significantly higher responses to erotic film than the postmenopausal women (mean age, 57 years). It was concluded that the menopause does result in a decrease in sexual response as assessed by vaginal pulse amplitude. However, it was not established that the magnitude of change noted is sufficient to cause any sexual dysfunction.