甾体激素对大鼠脑突触质膜上甘氨酸受体结合的影响

Effect of steroid on binding properties of glycine receptors on synaptic plasma membrane from rats

制备大鼠脑突触质膜，排除胞液污染，用放射配体结合的方法，以［３Ｈ］甘氨酸为标记配体。结果测得甘氨酸受体结合的饱和曲线，Ｓｃａｔｃｈａｒｄ作图为一条直线，结合容量Ｂｍａｘ为每ｍｇ蛋白（２６±４）ｐｍｏｌ，平衡解离常数Ｋｄ为（１７３±１５）ｎｍｏｌ／Ｌ；士的宁取代实验显示：脑干部甘氨酸受体为士的宁敏感型，余脑部为士的宁不敏感型。甾体激素取代实验提示：孕酮对甘氨酸受体的结合有快速的抑制作用。

The synaptic membrane(SPM)was prepared from rat brain. There was no cytosolic contamination.The marked enzyme,LDH,was used to monitor the SPM purity.Using radioligand binding assay with[3H]glycine as a ligand,a saturated curve of glycine receptor binding was obtained and the scatchard plots showed a straight line,from which it was found that the binding capacity(Bo)was 26±4 pmol/mg protein and the equilibrium dissociation constant(Kd)was 173±15 nmol/L.The IC50 of glycine was 10-6 mol/L which was calculated from the displacement curve.The glycine receptor was strychnine-sensitive in the brainstem,but not in other brain regions.Inhibiting experiment with steroid hormones showed that progesterone had some effect on glycine receptor binding.