褪黑素及其受体与2型糖尿病

Melatonin ,its receptor and type 2 diabetes

褪黑素的分泌呈现昼低夜高的模式，而胰岛素分泌则与之相反。褪黑素对胰岛素的释放具有抑制作用，这主要是通过胰岛G细胞的褪黑素膜受体和胞内第二信使来实现的。在2型糖尿病患者和大鼠模型中，其血清褪黑索水平降低，且大鼠松果体内的5-羟色胺-N-乙酰基转换酶（AA—NAT）活性也降低。有关褪黑素受体基因多态性研究发现，褪黑素受体1B基因突变的个体发生2型糖尿病的风险增加。因此，阻断褪黑素对胰岛素的抑制作用可能为防治2型糖尿病开辟新的途径。

Melatonin secretion shows a high level at nights and low in the daytime. However,insulin secretion goes the opposite way of melatonin. Melatonin inhibits insulin secretion, which is achieved by the melatonin membrane receptors and second messengers at the pancreatic β-cells. Serum melatonin levels decreases in diabetic patients and rats models, and the arylalkylamine-N-acetyhransferase （AA-NAT） activity at the pineal gland of rats models also decreases. Studies on polymorphism of melatonin receptors have shown that individuals with the melatonin receptor 1 B mutation have high risk of type 2 diabetes. Therefore, controlling the melatonin-induced inhibition of insulin secretion may be a novel therapeutic method for the prevention and treatment of type 2 diabetes.