The effects of dehydroepiandrosterone (DHEA)/DHEA-sulfate (DHEAS) on the contraction responses of the clitoral cavernous smooth muscle from female rabbits.

INTRODUCTION

Dehydroepiandrosterone (DHEA) is a multifunctional steroid that is increasingly available as a supplement aimed at improving libido and well-being in postmenopausal women in the recent times. Together with its sulfate version, DHEA-sulfate (DHEAS), it is the most abundant steroid in humans. The clitoris is an important component of the female sexual response, with its increased vascular response during sexual arousal that results in erection.

AIMS: To elucidate the direct effects of DHEA/DHEAS on the vasomotor reactivity of the rabbit clitoral cavernosum.

METHODS

Twenty New Zealand white female rabbits weighing approximately 2.5-3 kg were used in the study.

MAIN OUTCOME MEASURES: The contractile response of clitoral cavernous smooth muscle strips in response to phenylephrine (PE; 10(-9)-10(-4) M) were observed in rabbits. Additionally, DHEA/DHEAS effects on phenylephrine-induced contraction and/or acetylcholine-induced relaxation of phenylephrine-induced contraction were measured.

RESULTS

DHEA/DHEAS did not elicit any remarkable response in the resting state. However, both DHEA and DHEAS evoked dose-dependent relaxations of PE-induced contraction. The contractile responses to high potassium were significantly decreased in the DHEA/DHEAS-pretreated strips, compared with the DHEA/DHEAS-nontreated strips. Additionally, contractions by Bay K 8644 (10(-7)-10(-6) M) treatment were also significantly inhibited by DHEA/DHEAS. DHEA-induced relaxation responses were stronger than DHEAS-induced relaxation responses. Various K channel blockers, tetraethylammonium (TEA; 1 mM, 10 mM), 4-aminopyridine (10 microM) and glibenclamide (10 microM) did not affect the DHEA/DHEAS-induced relaxation on muscle strips contracted by PE. Relaxation responses by acetylcholine or sodium nitroprusside (SNP) were not changed after DHEA/DHEAS pretreatment.

CONCLUSIONS

DHEA/DHEAS was found to induce a relaxation response in rabbit clitoral cavernosal smooth muscle, and this is thought to be mediated by direct inhibition of a voltage-dependent calcium channel.