The role of the sympathetic nervous system in female sexual arousal
Creators: name: Meston, Cindy May
Publisher: name: University of British Columbia
Year: 2009

description: In contrast to the long-held assumption that heightened sympathetic nervous system (SNS) activity inhibits sexual arousal in women, Meston and Gorzalka (1995) recently provided evidence for a facilitatory influence of SNS activation on physiological sexual arousal in women. The present investigation was aimed at further elucidating the role of the SNS in female sexual arousal by examining the time course of the effects of SNS activation on sexual arousal in women, by providing the first empirical test of the effects of SNS inhibition on physiological and subjective sexual arousal in women, and by examining the effects of SNS activation on sexual arousal in sexually dysfunctional women. In Experiment 1, 36 sexually functional women participated in two experimental sessions in which they viewed a neutral film followed by an erotic film. In one of these sessions, subjects were exposed to 20 mm of intense exercise prior to viewing the films. Subjective (self.report) and physiological (photoplethysmograph) sexual arousal were measured at either 5 mm, 15 mm, or 30 mm post-exercise. By measuring the effects of exercise on sexual arousal at these time intervals, Experiment 1 allowed for examination of high, moderate, and low levels of SNS activation on sexual responding. Acute exercise marginally decreased vaginal pulse amplitude (VPA) and had no effect on vaginal blood volume (VBV) responses to an erotic film when measured 5 mm post-exercise. At 15 mm post-exercise, exercise significantly increased WA and showed a trend toward increasing VBV responses. At 30 mm post-exercise, VBV responses to an erotic film were marginally increased and VPA responses showed a trend toward increasing. Acute exercise had no significant effect on subjective perceptions of sexual arousal in any of the experimental conditions. These findings suggest an optimal level of SNS activation for facilitation of physiological sexual arousal in women. Experiments 2 and 3 were designed to examine the effects of SNS inhibition, via clonidine administration, on sexual arousal in women. In Experiment 2, the effects of SNS inhibition on sexual arousal were examined following experimentally-induced nervous system arousal. Fifteen sexually functional women engaged in 20 mm of intense exercise during each of two experimental sessions. One hour prior to exercise, subjects received either 0.2 mg clonidine or a placebo. Clonidine significantly decreased WA, VBV, and subjective sexual responses to the erotic films. In Experiment 3, the effects of SNS inhibition on sexual arousal were examined during baseline arousal, i.e., in the absence of acute exercise. Fifteen sexually functional women participated in two experimental sessions in which they received either 0.2 mg clonidine or a placebo one hour prior to viewing the erotic films. Clonidine marginally decreased subjective ratings of sexual arousal but had no significant effect on VPA or VBV responses. The findings from Experiments 2 and 3 argue against the notion that SNS inhibition facilitates the initial stages of sexual arousal in women. In Experiment 4, the effects of SNS activation (via acute exercise) on sexual arousal were compared between 12 sexually functional women, 12 women with low sexual drive, and 12 women with either primary or secondary anorgasmia. Acute exercise significantly increased WA and VBV responses to an erotic film among sexually functional women and women with low sexual drive. Among anorgasmic women, exercise marginally decreased VPA while having no effect on VBV responses to an erotic film. Acute exercise had no significant effect on subjective perceptions of sexual arousal among either sexually functional, low sexual drive, or anorgasmic subjects. The results from Experiment 4 replicate and extend the findings of Meston and Gorzalka (1995) to a sample ofwomen with low sexual drive, and suggest an inhibitory influence of SNS activation on sexual arousal in anorgasmic women. These findings provide the first empirical evidence to suggest neurophysiological differences between women with and without orgasmic dysfunction. Together, Experiments 1 to 4 provide evidence for a primarily facilitatory role of SNS activation, and an inhibitory role of SNS inhibition on sexual arousal in women. These results have implications for deriving an etiological theory of sexual dysfunction in women and for developing new methods of treatment for women with sexual difficulties.