The role of serum testosterone in the accelerated extinction of a conditioned taste aversion in fluid deprived male rats.

Fluid deprivation decreases serum testosterone (T) levels and increases the rate of extinction of a conditioned taste aversion in Sprague-Dawley male rats. It has been suggested that the decreased serum levels may be the primary factor responsible for the accelerated extinction rates during fluid deprivation. To test the generality of this hypothesis, the effect of fluid deprivation on T levels and extinction rate was investigated in Fischer 344 male rats. Extinction rates were accelerated in Fischer 344 rats but T levels were not decreased. In a second study, the behavioral and hormonal responses of Fischer 344 and Sprague-Dawley males to fluid deprivation were compared. Extinction rates were increased in both strains of rat by fluid deprivation, but serum T levels were decreased in fluid-deprived Sprague-Dawley males and not Fischer 344 males. It was suggested that the accelerated extinction in fluid-deprived Sprague-Dawley males was primarily due to decreases in serum T levels, while the faster extinction in deprived Fisher 344 males could be accounted for by decreases in sensitivity to T.