糖尿病大鼠阴茎海绵体组织中SK3表达的研究

Diabetes mellitus reduces the expression of SK3 in rat cavernous tissues

目的:SK3是小电导型钙依赖钾通道之一,是内皮依赖性超极化因子(endothelium-derived hyperpolar-izing factor,EDHF)通路中关键物质,本研究探讨糖尿病对大鼠阴茎海绵体小电导钙激活性钾通道蛋白SK3表达的影响。方法:雄性SD大鼠60只,其中50只大鼠采用腹腔注射链脲佐菌素(streptozocin,STZ)制作糖尿病模型组(DM),注射STZ未能成模大鼠用作STZ药物对照组(STZ),其余10只大鼠用于空白对照组。造模成功后饲养8周,注射阿朴吗啡(apomorphine,APO)80μg/kg后,观察大鼠阴茎勃起情况;随后采用RT-PCR、Western印迹技术检测SK3mRNA和蛋白在大鼠阴茎海绵体中的表达水平。结果:DM组(26只)有14只大鼠阴茎勃起,勃起率为54%,STZ组(15只)和空白对照组(10只)勃起率均为100%。DM组SK3mRNA表达(0.50±0.09)显著低于STZ组(1.15±0.03)和空白对照组(1.21±0.04)(P<0.05)。DM组SK3蛋白表达(0.65±0.06)与STZ组(1.28±0.04)和空白对照组(1.34±0.05)相比存在显著差异(P<0.05)。STZ组和空白对照组之间大鼠阴茎勃起情况和SK3mRNA及蛋白表达无差异(P>0.05)。结论:糖尿病可明显降低大鼠阴茎勃起功能,且这可能与大鼠阴茎海绵体SK3表达减少密切相关。

Objective：SK3,one of the small conductance calcium-activated potassium channels,is the key substance of the endothelium-derived hyperpolarizing factor（EDHF）passway.This study aimed to investigate the expression of SK3 in the cavernous tissue of rats with diabetes mellitus（DM）.Methods：Twenty-six DM models were made by injection of streptozocin（STZ）out of 50 male Sprague-Dawley rats,and another 15 that failed to be modeled were included in an STZ group.Ten healthy male rats were taken as blank controls.Eight weeks later,the penile erectile function of the rats was detected by injection of apomorphine（APO）at 80 μg/kg,and the expression of SK3 in the cavernous tissue was determined by RT-PCR and Western blot.Results：Penile erection was observed in 14（54%）of the 26 DM rat models and in all the rats of the STZ and blank control groups.Both the mRNA and protein expressions of SK3 were significantly lower in the DM（0.50 ± 0.09 and 0.65 ± 0.06）than in the STZ（1.15 ± 0.03 and 1.28 ± 0.04）and blank control groups（1.21 ± 0.04 and 1.34 ± 0.05）（P 0.05）.There were no significant differences between the STZ and blank control groups in either penile erection or mRNA and protein expressions of SK3（P 0.05）.Conclusion：Diabetes mellitus can significantly reduce erectile function in rats,which may be related to the decreased expression of SK3 in the corpus cavernosum.