Testosterone is not required for the enhancement of sexual motivation by yohimbine.

Yohimbine HCL (2 mg/kg, 20 min prior to testing) administration was followed by significant decreases in the latencies to initial mount, intromission and ejaculation in castrated male rats bearing 2 mm testosterone-containing Silastic capsules 51 days after castration. Further, yohimbine stimulated copulatory activity in castrated, nonhormone-treated male rats up to 91 days after castration. Finally, yohimbine induced mounting in intact, nonreceptive female rats. These observations indicate that testosterone is not required for the enhancement of sexual motivation by yohimbine and support the suggestion that alpha 2-adrenoceptors are involved in the modulation of sexual arousal.