Interactive effects of fluid deprivation and testosterone on the expression of a sexually dimorphic conditioned taste aversion.

The effects of fluid deprivation on the sexually dimorphic rate of extinction of a conditioned taste aversion in rats was investigated. Under ad lib water conditions, males extinguished a conditioned taste aversion more slowly than females. However, when rats were fluid deprived, there was no difference in the extinction rates of females and males even when the more sensitive two-bottle test was used. This absence of the sexual dimorphism was due to a differential effect of deprivation on females and males. Fluid deprivation increased the rate of extinction of the male but had no effect on the extinction rate of the female. It was proposed that the more rapid extinction rate of the deprived male could be accounted for by a deprivation-induced change in a testosterone-dependent mechanism. This proposal was supported by demonstrating that injection of testosterone propionate blocked the effects of fluid deprivation on rate of extinction in the male rat.