褪黑激素对小鼠睾丸生精细胞凋亡和睾丸间质细胞nNOS表达的影响

目的：观察外源性褪黑激素(MT)对睾丸生精细胞凋亡和nNOS表达的影响，探讨MT诱导生精细胞凋亡的可能机制。方法：20d和30d小鼠，应用化学发光法检测血清睾酮浓度，TUNEL测定生精细胞凋亡，免疫组化，SABC法观察nNOS在睾丸中的表达。结果：20d和30d实验组血清中睾酮水平明显下降，TUNEL阳性生精细胞数显著增多，TUNEL阳性生精细胞数与睾酮浓度呈负相关；20d实验小鼠中睾丸间质nNOS阳性细胞数与对照组相比明显减少，且与睾酮浓度呈正相关，而与TUNEL阳性生精细胞数呈负相关。结论：MT具有促进生精细胞凋亡的作用，与睾酮分泌受抑制有关；青春期前MT引起生精细胞凋亡可能还与nNOS表达有关。

Effect of melatonin on apoptosis of spermatogenic cells and expression of nNOS in testis of mice

Objective: To investigate the effect of melatonin (MT) on the apoptosis of spermatogenic cells and the expression of nNOS in testis and to explore the possible mechanism for the apoptosis of spermatogenic cells induced by MT. Methods: Male mices of 20d and 30d were divided into the control group and experimental groups. Chemiluminenscence,TUNEL and immunohistochemistry were used to determine the levels of serum testosterone,the apoptosis of spematogenic cells and the expression of nNOS. Results:Compared with the control group,the levels of serum testosterone were decreased evidently,the number of TUNEL positive spermatogenic cells was increased obviously and had negative correlation with the levels of serum testosterone.In experimental groups of 20d,the number of nNOS positive cells was reduced by MT and had positive correlation with the levels of serum testosterone and negative correlation with the number of TUNEL positive spermatogenic cells. Conclusion:Exo-melatonin can promote the apoptosis of spermatogeni cells,which is related to the reduction of the levels of serum testosterone.In preadolescence,the apoptosis of spermatogenis cells induced by MT has correlation with both the secretion of testosterone and the expression of nNOS in leydig cells.