Pseudo-castration effects of social isolation on extinction of a taste aversion

The effects of social isolation on the slow rate of extinction of a conditioned taste aversion exhibited by male rats were investigated. When the males were isolated for six weeks prior to poisoning, they showed a nontypical, rapid rate of extinction from the conditioned taste aversion. The isolation had no effect on the already rapid rate of extinction exhibited by the females. Behaviorally, the change in the rate of extinction in the male following social isolation is identical to the change in rate that occurs following castration of the male. It was therefore proposed that isolation increased the rate of extinction in the male by decreasing the availability of testosterone. This proposal was supported by the finding that socially isolated males had lower plasma testosterone levels than did non-isolated males.