人胚胎下丘脑褪黑素受体鉴定及其生物学特性

Identification and characteristics of melatonin receptor in human embryonic hypothalamus

目的为证实人胚胎下丘脑是否存在褪黑素受体（ＭＲ），以及ＧＴＰγＳ和电解质对ＭＲ的影响，以阐明褪黑素（Ｍ）生物学特性及对内分泌系统作用的机制。方法应用放射配体结合法检测人胚胎下丘脑〔１２５Ｉ〕Ｍ特异结合。结果１．人胚胎下丘脑〔１２５Ｉ〕Ｍ特异结合的Ｓｃａｔｃｈａｒｄ分析：最大结合容量（Ｂｍａｘ）为（１．１５±０．３２）ｆｍｏｌ／ｍｇ蛋白质；平衡解离常数（Ｋｄ）为（３６±８）ｐｍｏｌ／Ｌ；２．动力学分析表明为可逆性结合；３．特异性分析表明对Ｍ高度特异性；４．１０μｍｏｌ／Ｌ和５０μｍｏｌ／ＬＧＴＰγＳ使〔１２５Ｉ〕Ｍ特异结合降低，且有剂量依赖性。结论实验结果表明人胚胎下丘脑存在〔１２５Ｉ〕Ｍ特异结合位点。ＧＴＰγＳ对〔１２５Ｉ〕Ｍ特异结合有明显抑制作用。

Objective To verify whether there exists melatonin receptor in human embryonic hypothalamus. Methods Specificbindingofmelatonintoembryonic hypothalamus was measured by radioligand binding assay. Results Themaximumbindingcapacity(Bmax) was (1.15±0.32)fmol/mg protein and equilibrium dissociation constant (Kd) was (36±8)pmol/L. GTPγS dose dependently inhibited the binding. Conclusion The results demonstrate the presence of specific binding of melatonin in human embryonic hypothalamus. GTPγS inhibits the binding, indicating that putative melatonin receptor is coupled to G proteins.