Effect of Epimedium brevicornum Maxim extract on elicitation of penile erection in the rat

Objectives. To investigate the effect and mechanism of a Chinese medicine (Epimedium brevicornum Maxim [EbM]) on elicitation of penile erection in the rat. Methods. Adult male Sprague-Dawley rats were used. The penile intracavernous pressure (ICP) was monitored. Intracavernous administration of different doses (30, 100, 300, 1000, 3000, 6500, and 10,000 mu g/ 0.1 mL) of EbM extract and saline 0.1 mL was done. Intracavernous N-G-nitro-L-arginine methyl ester (L-NAME) (120 mu g) was administered, followed by EbM extract 300 mu g 10 minutes later. EbM extract (20, 10, and 10 mu g) was stereotaxically delivered into the intracerebral ventricle, paraventricular nucleus of the hypothalamus, and hippocampus, respectively. Results. After intracavernous administration of 30 or 100 mu g EbM extract, no significant change in ICP was noted. All other doses (300 to 10,000 mu g) of EbM extract elicited a significant increase in ICP, with the greatest peak at 99.7 +/- 0.3 mm Hg (resting 7.8 +/- 1.0 mm Hg) after application of 6500 mu g EbM extract. No change in ICP occurred with administration of L-NAME followed by EbM extract. Furthermore, intracavernous saline or administration of EbM extract into the intracerebral ventricle, paraventricular nucleus of the hypothalamus, or hippocampus was ineffective in inducing a significant change in ICP. Conclusions. These results suggest that intracavernous administration of EbM extract may elicit penile erection in the rat. Nitric oxide may be involved in this penile erection-inducing effect. No central neural effect of EbM extract may exist in the elicitation of penile erection.