Ginkgo biloba extract treatment increases noncontact erections and central dopamine levels in rats: role of the bed nucleus of the stria terminalis and the medial preoptic area.

RATIONALE: Penile erection is necessary for successful copulation in males. The extract of Ginkgo biloba leaves (EGb 761) significantly facilitates copulation in male rats, but the effect of EGb 761 on noncontact erection (NCE) remains unknown. OBJECTIVE: The present study was conducted to evaluate the influence of EGb 761 on NCE in male rats. MATERIALS AND METHODS: Adult Long-Evans male rats were treated with 50 mg/kg of EGb 761 (experimental group) or distilled water (control group) by gavage for 14 days. The NCE test was carried out after 14 days of EGb 761 treatment, and the latency and the numbers of NCE were recorded. Approximately 14 h following the NCE behavioral tests, animals were sacrificed by means of decapitation, and levels of dopamine in the bed nucleus of the stria terminalis (BNST) and medial preoptic area (MPOA) were measured by means of high-pressure liquid chromatography with electrochemical detection. RESULTS: Chronic treatment with EGb 761 significantly decreased the NCE latency, but increased the number of NCEs and the dopamine levels in the BNST and MPOA in rats compared to the controls. CONCLUSION: Treatment with EGb 761 increased both NCEs and the dopamine contents in the BNST and the MPOA. These results suggest that enhanced NCEs in the rats administered with EGb 761 may be related to dopaminergic activity in the BNST and MPOA.