Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin, Kerala, India.
Biogerontology. 2010 Apr;11(2):151-66. doi: 10.1007/s10522-009-9237-z. Epub 2009 Jun 24.
We investigated acetylcholine esterase (AChE) activity, acetylcholine and muscarinic M1, M3 receptors kinetics in the cerebral cortex of young and old streptozotocin induced and insulin treated diabetic rats. The role of muscarinic receptors in intracellular calcium release from pancreatic islets was studied in vitro. Wistar rats of 7 and 90-weeks old were used. All studies were done in cerebral cortex. AChE assay was done by spectrophotometric method. Radioreceptor binding assays were done for Acetylcholine, Muscarinic M1 and M3 receptors using specific ligands. Calcium imaging was done using fluo4-AM in pancreatic cells. Ninety-weeks old control rats showed significantly decreased Vmax and increased Km for AChE compared to 7-weeks old control rats. An increased Vmax observed in both 7 and 90-weeks old diabetic groups with significant decrease in Km. Scatchard analysis using specific agonists showed significant decrease in the B (max) and K (d) of acetylcholine and muscarinic M1 receptors in 90-weeks old control rats compared to 7-weeks old control. Binding studies for M3 receptors showed no significant change compared to 7-weeks old control. Acetylcholine, muscarinic M1 and M3 receptor number significantly increased in 90-weeks old diabetic rat groups compared to their respective controls. Insulin treatment significantly reversed the binding parameters to near control compared to diabetic group. In vitro studies showed that acetylcholine through muscarinic M1 and M3 receptors' stimulated calcium release from the pancreatic islets. Thus our studies suggest that Insulin signaling play an important part in differentially regulating pancreatic cholinergic activity, and the diabetes mediated cortical dysfunctions with age.
我们研究了年轻和老年链脲佐菌素诱导和胰岛素治疗的糖尿病大鼠大脑皮层中的乙酰胆碱酯酶（AChE）活性、乙酰胆碱和毒蕈碱 M1、M3 受体动力学。在体外研究了毒蕈碱受体在胰腺胰岛细胞内钙释放中的作用。使用 7 周和 90 周龄的 Wistar 大鼠。所有研究均在大脑皮层中进行。通过分光光度法测定 AChE 测定法。使用特定配体进行放射性受体结合测定，以测定乙酰胆碱、毒蕈碱 M1 和 M3 受体。使用 fluo4-AM 在胰腺细胞中进行钙成像。与 7 周龄的对照组相比，90 周龄的对照组大鼠的 AChE 的 Vmax 明显降低，Km 值增加。在 7 周龄和 90 周龄的糖尿病组中均观察到 Vmax 增加，Km 值显著降低。使用特异性激动剂进行 Scatchard 分析表明，与 7 周龄的对照组相比，90 周龄的对照组大鼠的乙酰胆碱和毒蕈碱 M1 受体的 B（max）和 K（d）显著降低。与 7 周龄的对照组相比，M3 受体的结合研究没有明显变化。与各自的对照组相比，90 周龄的糖尿病大鼠组的乙酰胆碱、毒蕈碱 M1 和 M3 受体数量显著增加。与糖尿病组相比，胰岛素治疗显著将结合参数恢复到接近对照组。体外研究表明，乙酰胆碱通过毒蕈碱 M1 和 M3 受体刺激胰腺胰岛细胞内钙释放。因此，我们的研究表明，胰岛素信号在调节胰腺胆碱能活性以及年龄相关的糖尿病介导的皮质功能障碍方面发挥着重要作用。
