The Effect Of Soybean Isoflavone On Development Of The System Of Reproduction And Sex Hormone Receptor In Corpus Cavernosum Penis In Male SD Rats

Objective To explore the effect of soybean isoflavone on the growth and development of the testis , epididymis and penis ,and sex hormone receptor in corpus cavernosum penis and erectile function in male SD rats. Methods 10 weeks (phyloneanic) and 4 weeks(juvenile) male SD rats, each of which is 30, discern to separate five groups: the control, the model, and low, moderate , high dose of soybean isoflavone groups .By intragastric administration in phyloneanic and juvenile rats for 90 d , the changes of body mass and testis , epididymis, penis index in the control (physiological saline), the model(0.1 mg/d DES), low(2 mg/kg), moderate(20 mg/kg), high dose(100 mg/kg) of soybean isoflavone groups were observed, and by HE decoration the structural changes of testis , epididymis and penis were observed. In juvenile rats, At the end of the study, testosterone,LH and FSH were surveied and apomorphine-induced erection test was used to evaluate erectile function; the penis was examined carefully forits development. Frozen sections of the penile shaft were prepared and stained with TRITC-phalloidin. The stained sections were scanned under the laser confocal system and cavernosal smooth muscles and collagen fibers were inspected. The mRNA of sex hormone receptor in corpus cavernosum penis were observed by RT-PCR, and the protein of it were observed by immuocytochemistry and Western Blotting. Results in phyloneanicrats, there were no significant differences in penis, testis , epididymis index and body weight between the low, moderate, high dose of soybean isoflavone groups and the control group ( P>0.05); in phyloneanic rats, there were no significant differences in penis and epididymis index between the low, moderate, high dose of soybean isoflavone groups and the control group ( P>0. 05); and there were significant differences in testis index between the high dose (3.21±0.07)of soybean isoflavone group and the control group(3.71±0.45)( P<0.05), no significant differences between the low, moderatedose of soybean isoflavone groups and the control group (P>0.05); No significant differences in body weight were found among the low, moderate dose of soybean isoflavone groups and the control group (P>0. 05), and there were significantdifferences between the high dose group and the control group (P<0.05).In the result of HE decoration , there was no changes of epididymis and penis in the low, moderate, high dose of soybean isoflavone groups of phyloneanic and juvenile male SD rats, and in high dose of soybean isoflavone groups, hypoevolutism and various degrees of dyszoospermia of testis were found.The cavernosal smooth muscle/collagen content ratio and the content of testosterone decreased in moderate , high dose of soybean isoflavone groups compared to the control (P<0.05).There were no significant differences in expression of AR and ERa, and there was no significant difference between low dose group and the control.but the expression of ERβdecreased in moderate , high dose groups. Conclusion Low dose (2mg/kg) daidzein had noapparent effects on the growth of male reproduction, But higher doses (≥20 mg/kg)daidzein could cause cavernosal smooth muscle/collagen content ratio reduction and erectile function attenuation although without affecting penile growth and development and the decreasation of testosterone in blood and ERβin corpuscavernosum penis.Soybean isoflavone (≥100mg/kg) inhibits the growth and development of the testes in juvenile rats.