Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab, India.
National Agri-Food Biotechnology Institute, Sector 81, S.A.S. Nagar, Punjab, India.
Curr Neurovasc Res. 2020;17(3):249-258. doi: 10.2174/1567202617666200415142211.
Diabetes is a chronic metabolic disorder affecting the central nervous system. A growing body of evidence has depicted that high glucose level leads to the activation of the transient receptor potential melastatin 2 (TRPM2) channels. However, there are no studies targeting TRPM2 channels in diabetes-induced cognitive decline using a pharmacological approach.
The present study intended to investigate the effects of 2-aminoethoxydiphenyl borate (2-APB), a TRPM2 inhibitor, in diabetes-induced cognitive impairment.
Streptozotocin (STZ, 50 mg/kg, i.p.) was used to induce diabetes in rats. Animals were randomly divided into the treatment group, model group and age-matched control and pre se group. 2-APB treatment was given for three weeks to the animals. After 10 days of behavioural treatment, parameters were performed. Animals were sacrificed at 10th week of diabetic induction and the hippocampus and cortex were isolated. After that, protein and mRNA expression study was performed in the hippocampus. Acetylcholinesterase (AchE) activity was done in the cortex.
Our study showed the 10th week diabetic animals developed cognitive impairment, which was evident from the behavioural parameters. Diabetic animals depicted an increase in the TRPM2 mRNA and protein expression in the hippocampus as well as increased AchE activity in the cortex. However, memory associated proteins were down-regulated, namely Ca2+/calmodulin-dependent protein kinase II (CaMKII-Thr286), glycogen synthase kinase 3 beta (GSK-3β-Ser9), cAMP response element-binding protein (CREB-Ser133), and postsynaptic density protein 95 (PSD-95). Gene expression of parvalbumin, calsequestrin and brain-derived neurotrophic factor (BDNF) were down-regulated while mRNA level of calcineurin A/ protein phosphatase 3 catalytic subunit alpha (PPP3CA) was upregulated in the hippocampus of diabetic animals. A three-week treatment with 2-APB significantly ameliorated the alteration in behavioural cognitive parameters in diabetic rats. Moreover, 2-APB also down-regulated the expression of TRPM2 mRNA and protein in the hippocampus as well as AchE activity in the cortex of diabetic animals as compared to diabetic animals. Moreover, the 2-APB treatment also upregulated the CaMKII (Thr-286), GSK-3β (Ser9), CREB (Ser133), and PSD-95 expression and mRNA levels of parvalbumin, calsequestrin, and BDNF while mRNA level of calcineurin A was down-regulated in the hippocampus of diabetic animals.
This study confirms the ameliorative effect of TRPM2 channel inhibitor in the diabetes- induced cognitive deficits. Inhibition of TRPM2 channels reduced the calcium associated downstream signaling and showed a neuroprotective effect of TRPM2 channels in diabetesinduced cognitive impairment.
糖尿病是一种影响中枢神经系统的慢性代谢性疾病。越来越多的证据表明，高葡萄糖水平会导致瞬时受体电位 melastatin 2 (TRPM2)通道的激活。然而，目前还没有研究使用药理学方法针对糖尿病引起的认知功能下降的 TRPM2 通道。
本研究旨在探讨 TRPM2 抑制剂 2-APB 在糖尿病诱导的认知障碍中的作用。
链脲佐菌素 (STZ，50mg/kg，ip) 用于诱导大鼠糖尿病。动物随机分为治疗组、模型组和年龄匹配的对照组和预给药组。动物给予 2-APB 治疗 3 周。经过 10 天的行为治疗后，进行参数检测。在糖尿病诱导的第 10 周，动物被处死，海马体和皮质被分离。之后，在海马体中进行蛋白质和 mRNA 表达研究。在皮质中进行乙酰胆碱酯酶 (AchE) 活性测定。
我们的研究表明，第 10 周的糖尿病动物出现了认知障碍，这从行为参数中可以明显看出。糖尿病动物的海马体中 TRPM2 mRNA 和蛋白表达增加，皮质中 AchE 活性增加。然而，与记忆相关的蛋白表达下调，即钙/钙调蛋白依赖性蛋白激酶 II (CaMKII-Thr286)、糖原合成酶激酶 3β (GSK-3β-Ser9)、cAMP 反应元件结合蛋白 (CREB-Ser133) 和突触后密度蛋白 95 (PSD-95)。海马体中 parvalbumin、calsequestrin 和脑源性神经营养因子 (BDNF) 的基因表达下调，而糖尿病动物的 calcinurin A/蛋白磷酸酶 3 催化亚基α (PPP3CA) mRNA 水平上调。2-APB 治疗 3 周可显著改善糖尿病大鼠的行为认知参数改变。此外，2-APB 还可下调糖尿病动物海马体中 TRPM2 mRNA 和蛋白的表达以及皮质中 AchE 的活性。此外，2-APB 治疗还可上调 CaMKII(Thr-286)、GSK-3β(Ser9)、CREB(Ser133)和 PSD-95 的表达和海马体中 parvalbumin、calsequestrin 和 BDNF 的 mRNA 水平，同时下调糖尿病动物海马体中的 calcineurin A mRNA 水平。
本研究证实了 TRPM2 通道抑制剂在糖尿病诱导的认知功能障碍中的改善作用。TRPM2 通道的抑制减少了钙相关的下游信号，并显示了 TRPM2 通道在糖尿病诱导的认知功能障碍中的神经保护作用。
