二甲双胍激活AMPK/mTOR通路上调阴茎海绵体自噬增强老年ED大鼠勃起功能

Metformin enhances erectile function in rats with aging-induced erectile dysfunction by activating AMPK/mTOR pathway-regulated autophagy in corpus cavernosum

目的探讨二甲双胍对老年大鼠勃起功能的影响以及其对阴茎海绵体组织纤维化、自噬的调控和相关潜在机制。方法 40只健康2月龄雄性SD大鼠等分为4组,阿朴吗啡(apomorphine,APO)阴茎勃起实验筛选老年勃起功能障碍(erectile dysfunction,ED)大鼠。A组(正常对照组)从2月龄时开始每日生理盐水灌胃2个月,无ED;B、C、D组为ED大鼠从18月龄时开始每日分别生理盐水灌胃(ED对照组)、二甲双胍(300 mg·kg^-1·d^-1)灌胃(二甲双胍组)、二甲双胍(300 mg·kg^-1·d^-1)灌胃同时腹腔注射compound C(0.2 mg·kg^-1·d^-1,二甲双胍+compound C组)2个月。电刺激测量勃起功能,Masson染色检测阴茎海绵体纤维化,Western blot、透射电镜检测自噬水平,免疫荧光、Western blot检测AMPK/mTOR通路蛋白表达。结果与正常对照组比较,ED对照组勃起功能明显降低(P<0.05),阴茎海绵体纤维化加重,自噬和AMPK/mTOR通路被抑制(P<0.05);二甲双胍组大鼠轻度恢复勃起功能(P<0.05),改善阴茎海绵体纤维化,上调自噬水平(P<0.05),激活AMPK/mTOR通路(P<0.05),以上指标仍未达到正常对照组水平(P<0.05);二甲双胍+compound C组与ED对照组差异无统计学意义(P>0.05)。结论二甲双胍能改善老年ED大鼠阴茎海绵体纤维化,增强勃起功能,其机制可能与激活AMPK/mTOR通路上调自噬有关。

Objective To investigate the effect of metformin on erectile function and its regulation on cavernous fibrosis and autophagy in aged rats, and explore the underlying mechanism. Methods Forty healthy 2-month-old male SD rats were randomly divided into groups A, B, C and D. APO at a dose of 100 mg/kg was injected intraperitoneally to the rats of the former group(at 2 months old) and of the latter 3 group(at 18 months old) to screen the rats with aging-induced erectile dysfunction. Those with ED from the latter 3 groups and those without ED in the group A were employed for the further studies. Group A(control group) was given intragastrical infusion of normal saline for 2 months from the age of 2 months. The rats of the latter 3 groups(18 months old) were injected inragastrically with normal saline, metformin at 300 mg·kg^-1·d^-1 alone and combined with 0.2 mg/kg compound C for 2 months, respectively. The erectile function was measured by electrical stimulation. The cavernous fibrosis was detected by Masson staining. The autophagy level was detected by Western blotting and transmission electron microscopy. The expression of AMPK/mTOR pathway related proteins was detected by immunofluorescence assay and Western blotting. Results Compared with the group A, the group B had significantly decreased erectile function(P<0.05), aggravated cavernous fibrosis, and inhibited autophagy and AMPK/mTOR pathway(P<0.05). Metformin treatment slightly restored the erectile function in the group C(P<0.05), alleviated the cavernous fibrosis, upregulated autophagy(P<0.05), and activated the AMPK/mTOR pathway(P<0.05). But these indicators still did not reach the levels of the group A(P<0.05). There were no significant differences in above indicators between group D and group B. Conclusion Metformin alleviates cavernous fibrosis and improves erectile function in aging-induced erectile dysfunction rats, which may be related to the activation of AMPK/mTOR pathway to up-regulate autophagy.