Dong Shiyun, Li Gang, Zheng Dan, Wu Jichao, Sun Dianjun, Yang Fan, Yu Xiangjing, Li Ting, Sun Aili, Liu Jiaqi, Zhong Xin, Xu Changqing, Lu Fanghao, Zhang Weihua
Department of Pathophysiology, Harbin Medical University, Harbin, China.
Cell Physiol Biochem. 2015;35(1):38-50. doi: 10.1159/000369673. Epub 2015 Jan 2.
Diabetic encephalopathy is a common complication of diabetes, and it may be involved in altering intracellular calcium concentrations ([Ca(2+)]i) at its onset. The calcium sensing receptor (CaSR) is a G-protein coupled receptor, however, the functional involvement of CaSR in diabetic encephalopathy remains unclear.
In this study, diabetic rats were modeled by STZ (50 mg/kg). At the end of 4, 8 and 12 weeks, the CaSR expression in hippocampus was analyzed by Western blot. In neonatal rat hippocampal neurons, the [Ca(2+)]i was detected by laser scanning confocal microscopy, the production of reactive oxygen species (ROS) in mitochondria, the level of NO and the mitochondrial transmembrane potential were measured by MitoSOX, DAF-FM and JC-1, respectively.
Our results showed in hippocampal neurons treated with high glucose, CaSR regulated [Ca(2+)]i through the PLC-IP3 pathway. CaSR expression was decreased and was involved in the changes in [Ca(2+)]i. Mitochondrial membrane potential, NO release and expression of p-eNOS decreased, while the production of ROS in mitochondria increased.
Down-regulation of CaSR expression was accompanied by neuronal injury, calcium disturbance, increased ROS production and decreased release of NO. Up-regulation of CaSR expression attenuated these changes through a positive compensatory protective mechanism to inhibit and delay diabetic encephalopathy in rats.
糖尿病性脑病是糖尿病常见的并发症，其发病初期可能涉及细胞内钙浓度（[Ca(2+)]i）的改变。钙敏感受体（CaSR）是一种G蛋白偶联受体，然而，CaSR在糖尿病性脑病中的功能作用仍不清楚。
在本研究中，用链脲佐菌素（STZ，50mg/kg）建立糖尿病大鼠模型。在4周、8周和12周结束时，通过蛋白质免疫印迹法分析海马中CaSR的表达。在新生大鼠海马神经元中，通过激光扫描共聚焦显微镜检测[Ca(2+)]i，分别用MitoSOX、DAF-FM和JC-1检测线粒体中活性氧（ROS）的产生、一氧化氮（NO）水平和线粒体跨膜电位。
我们的结果表明，在高糖处理的海马神经元中，CaSR通过磷脂酶C-肌醇三磷酸（PLC-IP3）途径调节[Ca(2+)]i。CaSR表达降低并参与了[Ca(2+)]i的变化。线粒体膜电位、NO释放和磷酸化内皮型一氧化氮合酶（p-eNOS）表达降低，而线粒体中ROS的产生增加。
CaSR表达下调伴随着神经元损伤、钙紊乱、ROS产生增加和NO释放减少。CaSR表达上调通过积极的代偿性保护机制减轻这些变化，以抑制和延缓大鼠糖尿病性脑病。
