Combination of testosterone and vardenafil increases female sexual functioning in sub-primed rats.

INTRODUCTION: Hypoactive sexual desire disorder (HSDD) is a common problem in women and may have a negative impact on quality of life. A recent clinical study shows an increase in sexual drive of HSDD women after cotreatment of testosterone and vardenafil (phosphodiesterase type 5 inhibitor). AIM: In this study, we investigated the effect of testosterone and vardenafil on sexual activity in female rats. MAIN OUTCOME MEASURES: Proceptive (darts and hops), receptive (lordosis), and paced-mating (percentages after exits and contact-return latencies) behaviors were quantified. METHODS: Ovariectomized female rats, sub-primed with only estradiol and fully primed with estradiol and progesterone, were tested in a paced-mating sex test and sexual behaviors were quantified. The sub-primed rats are thought to model HSDD. The effect of testosterone (100 and 300 microg, subcutaneous [SC]) and vardenafil (10 mg/kg, per os [PO]) alone and testosterone (300 microg, SC) in combination with vardenafil (3 and 10 mg/kg, PO) were tested. We also studied the effects of testosterone (300 microg, SC) + intracerebroventricular (ICV) injections of vardenafil (25 and 50 microg) on sexual activity. RESULTS: No effect of testosterone and vardenafil alone was found, but cotreatment of testosterone and vardenafil (PO) caused a significant increase in proceptive and receptive behavior in the sub-primed female rats. Testosterone and vardenafil did not affect fully primed females. ICV administration of vardenafil combined with systemic testosterone, on the other hand, had no effect on sexual activity in both sub-primed and fully primed female rats. CONCLUSIONS: We conclude that cotreatment of subcutaneous testosterone and oral vardenafil increase sexual activity in sub-primed female rats. Our data supports the human finding that combination treatment of testosterone and vardenafil could be used as a new treatment for women with HSDD.