Kooptiwut Suwattanee, Hanchang Wanthanee, Semprasert Namoiy, Junking Mutita, Limjindaporn Thawornchai, Yenchitsomanus Pa-thai
Department of PhysiologyDepartment of AnatomyDivision of Molecular MedicineDepartment of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
Department of PhysiologyDepartment of AnatomyDivision of Molecular MedicineDepartment of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
J Endocrinol. 2015 Mar;224(3):215-24. doi: 10.1530/JOE-14-0397. Epub 2014 Dec 15.
Hypogonadism in men is associated with an increased incidence of type 2 diabetes. Supplementation with testosterone has been shown to protect pancreatic β-cell against apoptosis due to toxic substances including streptozotocin and high glucose. One of the pathological mechanisms of glucose-induced pancreatic β-cell apoptosis is the induction of the local rennin-angiotensin-aldosterone system (RAAS). The role of testosterone in regulation of the pancreatic RAAS is still unknown. This study aims to investigate the protective action of testosterone against glucotoxicity-induced pancreatic β-cell apoptosis via alteration of the pancreatic RAAS pathway. Rat insulinoma cell line (INS-1) cells or isolated male mouse islets were cultured in basal and high-glucose media in the presence or absence of testosterone, losartan, and angiotensin II (Ang II), then cell apoptosis, cleaved caspase 3 expression, oxidative stress, and expression of angiotensin II type 1 receptor (AGTR1) and p47(phox) mRNA and protein were measured. Testosterone and losartan showed similar effects in reducing pancreatic β-cell apoptosis. Testosterone significantly reduced expression of AGTR1 protein in INS-1 cells cultured in high-glucose medium or high-glucose medium with Ang II. Testosterone decreased the expression of AGTR1 and p47(phox) mRNA and protein in comparison with levels in cells cultured in high-glucose medium alone. Furthermore, testosterone attenuated superoxide production when co-cultured with high-glucose medium. In contrast, when cultured in basal glucose, supplementation of testosterone did not have any effect on cell apoptosis, oxidative stress, and expression of AGT1R and p47(phox). In addition, high-glucose medium did not increase cleaved caspase 3 in AGTR1 knockdown experiments. Thus, our results indicated that testosterone prevents pancreatic β-cell apoptosis due to glucotoxicity through reduction of the expression of ATGR1 and its signaling pathway.
男性性腺功能减退与2型糖尿病发病率增加有关。已证明补充睾酮可保护胰腺β细胞免受包括链脲佐菌素和高糖在内的有毒物质诱导的凋亡。葡萄糖诱导的胰腺β细胞凋亡的病理机制之一是局部肾素-血管紧张素-醛固酮系统（RAAS）的激活。睾酮在调节胰腺RAAS中的作用仍不清楚。本研究旨在通过改变胰腺RAAS途径来研究睾酮对葡萄糖毒性诱导的胰腺β细胞凋亡的保护作用。将大鼠胰岛素瘤细胞系（INS-1）细胞或分离的雄性小鼠胰岛在基础和高糖培养基中培养，分别添加或不添加睾酮、氯沙坦和血管紧张素II（Ang II），然后检测细胞凋亡、裂解的半胱天冬酶3表达、氧化应激以及血管紧张素II 1型受体（AGTR1）和p47（phox）mRNA及蛋白的表达。睾酮和氯沙坦在减少胰腺β细胞凋亡方面显示出相似的效果。睾酮显著降低了在高糖培养基或含Ang II的高糖培养基中培养的INS-1细胞中AGTR1蛋白的表达。与仅在高糖培养基中培养的细胞相比，睾酮降低了AGTR1和p47（phox）mRNA及蛋白的表达。此外，睾酮与高糖培养基共培养时可减轻超氧化物的产生。相反，在基础葡萄糖培养基中培养时，添加睾酮对细胞凋亡、氧化应激以及AGT1R和p47（phox）的表达没有任何影响。此外，在AGTR1基因敲低实验中，高糖培养基并未增加裂解的半胱天冬酶3。因此，我们的结果表明，睾酮通过降低ATGR1及其信号通路的表达来防止葡萄糖毒性诱导的胰腺β细胞凋亡。
