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Sexual behaviour and serotonergic type 2A stereotypic behaviour in male and female rats : the effects of stress and corticosteroids

University of British Columbia

Both chronic psychosocial stress and chronic administration of corticosterone have been shown to alter serotonergic type 2A (5-HT2A) receptor activity. A non-invasive behavioural index of 5-HT2A receptor activity is the frequency of "wet dog shakes" (WDS) or serotonergic stereotypy. In addition to WDS, 5-HT2A receptors mediate effects on sexual behaviour in the rat, in particular, inhibition in the male and stimulation in the female. In the present series of experiments, the potential involvement of stress and corticosterone in the regulation of WDS and sexual behaviour in the male and female rat was investigated. In Experiments 1-4, chronic exposure to several different forms of psychosocial stress was found to facilitate female and inhibit male rat sexual behaviour while concurrently increasing the display of WDS in both sexes. In Experiment 5, nefazodone, an antidepressant with 5-HT2A antagonistic properties, blocked the effects of stress on WDS but not sexual behaviour in female rats. In Experiments 6-7, the corticosterone synthesis inhibitor, metyrapone, blocked the effects of stress on sexual proceptivity and WDS in female rats. Metyrapone blocked the effects of stress on WDS but not sexual behaviour in male rats. In Experiments 8-9, high doses of corticosterone administered chronically facilitated female and inhibited male rat sexual behaviour while concurrently increasing WDS in both sexes. In Experiments 10-11, the 5-HT2A antagonist ketanserin was found to completely attenuate the effects of corticosterone on sexual behaviour and WDS in both male and female rats. In Experiments 12-13, the acute administration of corticosterone was found to exert no effect on either sexual behaviour or WDS in male or female rats. The present results indicate that both chronic corticosterone treatment and exposure to chronic stress inhibit male and facilitate female sexual behaviour while concurrently increasing WDS behaviour. The stress-induced facilitation of WDS appears to be related to elevated corticosterone levels and is suggestive of increased 5-HT2A activity. Both corticosterone and stress exerted effects on sexual behaviour in the direction that would be predicted by increased 5-HT2A activity. While the effects of corticosterone on sexual behaviour appear to be mediated by 5-HT2A activity, the effects of stress on sexual behaviour do not appear to be related to either elevations in corticosterone levels or alterations in 5-HT2A activity.

Thesis/Dissertation

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2009-07-02

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http://hdl.handle.net/2429/9976

Psychology

University of British Columbia

UBCV

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