小鼠脾脏褪黑素受体及其昼夜节律的研究

Circadian rhythm of melatonin receptor in the mouse spleen

目的：研究小鼠脾脏是否存在褪黑素（Ｍ）结合位点，该结合位点是否存在昼夜节律。方法：应用放射配体结合法检测小鼠脾脏Ｍ结合位点（ＭＲ）。每４ｈ处死一批动物，研究不同时间脾脏ＭＲ的差异；分别持续光照及注射Ｍ２１ｄ，观察ＭＲ结合量及昼夜节律的改变。结果：小鼠脾脏存在ＭＲ，其特点为低结合容量，高亲和力，对Ｍ具高度特异性，符合特异结合位点的基本条件；昼夜节律研究显示，ＭＲ结合量峰值在１２：００～１６：００，谷值在０：００～４：００，Ｆ检验峰谷值间差异显著（Ｐ＜０．０１）。结论：小鼠脾脏存在ＭＲ，其ＭＲ有昼夜节律变化；持续光照及注射Ｍ不影响ＭＲ节律，表明ＭＲ昼夜节律的机制是自主的，具生理学意义。

Objective: To determine whether there exists melatonin receptor (MR) in the mouse spleen and the circadian rhythm (CR) in MR. Methods: Specific binding of melatonin to the mouse spleen was measured by radioligand binding assay. Results: The results revealed the maximum binding capacity (Bmax) was (1.250.21) fmol/mg protein and equilibrium constant (Kd)was (59.510.1) pmol/L. The peak values of Bmax of MR was from 12:00 to16:00 and the trough values was between 0:00 to 4:00. The difference between them was significant statistically. CR of MR showed no change when continued light (3 weeks) and injected melatonin in peritoneum (3 weeks). Conclusion: MR is present in the mouse spleen and there exists CR of MR in the mouse spleen. It is indicated that CR of MR in spleen is independent from that of melatonin.