Testosterone as appetitive and discriminative stimulus in rats: sex- and dose-dependent effects

Stimulus properties of subcutaneously injected testosterone were studied in male and female rats. In a conditioned place preference procedure, dose-dependent effects (doses: 0, 0.5, and 1 mg/kg) were observed in males. In females, no place preference could be established (doses: 0, 1, and 3 mg/kg). In addition, 1 mg/kg testosterone acquired discriminative stimulus control in male rats in a taste aversion procedure. Animals injected with this hormone prior to saccharin-LiCl pairings and with its vehicle prior to saccharin-NaCl pairings suppressed fluid intake following the administration of testosterone and not following the administration of the vehicle. Subsequent generalization tests revealed dose-dependent stimulus control of this hormone (range of substitution doses: 0.125-2 mg/kg). It is concluded from the results that at least pharmacological (supraphysiological) doses of testosterone may act as appetitive stimuli in male rats, but not in female rats. Furthermore, in male rats (pharmacological doses of) testosterone also possess discriminative stimulus properties.