OBJECTIVETo investigate the effect of Bushengzhuyang Fang (Yangjing Capsule, YJC) on penile erectile function and its action mechanisms in rats.

METHODSFifty-six male SD rats were randomly divided into seven groups of equal number: blank control, daidzein, daidzein + testosterone, daidzein + sildenafil, daidzein + low-dose YJC, daidzein + medium-dose YJC, and daidzein + high-dose YJC. The rats in the blank control group were treated intragastrically with normal saline and those in the other groups with daidzein at the dose of 100 mg per kg per day for 30 days. Then the last five groups received additionally testosterone (4 mg per kg per day), sildenafil (2.5 mg per kg per day), low-dose YJC, (0.315 mg per kg per day), medium-dose YJC (0.63 mg per kg per day), and high-dose YJC (1. 26 mg per kg per day), respectively. At 0, 30 and 60 days of treatment, we observed the apomorphine-induced spontaneous erectile response and pathological changes in the corpus cavernosum of the rats, recorded the number of penile erection and erectile incubation period, and determined the serum levels of testosterone (T) and luteinizing hormone (LH).

RESULTSAt 30 days of treatment, the number of apomorphine-induced erections was decreased, the erectile incubation period prolonged, and the serum levels of T and LH reduced remarkably in all groups of rats (P < 0.05). Compared with the findings at 30 days, the number of penile erections was significantly decreased at 60 days in the daidzein group (1.39 ± 0.42 vs 2.67 ± 0.33, P < 0.05) and daidzein + low-dose YJC group (1.33 ± 0.49 vs 2.83 ± 0.61, P < 0.05); the erectile incubation period was markedly ex- tended ([16.33 ± 3.11] vs [8.50 ± 0.93] min and [15.50 ± 3.21] vs [8.63 ± 1.54] min, P < 0.05); and the serum levels of T ([5.34 ± 0.89] vs [1.24 ± 0.30] ng/ml and [5.28 ± 1.12] vs [2.07 ± 0.76] ng/ml, P < 0.05) and LH ([3.62 ± 0.37] vs [2.09 ± 0.12] ng/ml and [3.79 ± 0.28] vs [2.17 ± 0.33] ng/ml, P < 0.05) were significantly reduced in the daidzein and daidzein + low-dose YJC groups, respectively. Pathological examination revealed slightly decreased cavernous sinuses and blood vessels in the corpus cavernosum of the rats in the daidzein + testosterone, daidzein + sildenafil, daidzein + medium-dose YJC, and daidzein + high-dose YJC groups as compared with those in the blank control group.

CONCLUSIONHigh-dose Yangjing Capsule is efficacious for the recovery of erectile function in rats, especially for phytoestrogen-induced erectile dysfunction.