Laitinen J T, Saavedra J M
Section on Pharmacology, National Institute of Mental Health, Bethesda, Maryland 20892.
J Neurochem. 1990 Oct;55(4):1450-3. doi: 10.1111/j.1471-4159.1990.tb03161.x.
We studied the effects of cations on the binding of the melatonin (MT) agonist, 125I-MT, to MT receptors in the rat area postrema (AP) and suprachiasmatic nuclei (SCN), by using quantitative autoradiography in vitro. Ca2+ promoted agonist binding in the SCN but was without effect in the AP. Na+ induced a dose-dependent loss of agonist binding in both areas. This effect was more drastic in the SCN and also in the absence of divalent cations. The presence of 0.1-4.0 mM Ca2+ or Mg2+ partially and nonselectively reversed this Na(+)-elicited inhibition. The data agree with known cationic effects on agonist binding to other G protein-coupled receptors and deepen our understanding of the mammalian MT receptor.
我们通过体外定量放射自显影技术，研究了阳离子对褪黑素（MT）激动剂125I-MT与大鼠最后区（AP）和视交叉上核（SCN）中MT受体结合的影响。Ca2+促进了SCN中激动剂的结合，但对AP无影响。Na+在两个区域均引起激动剂结合的剂量依赖性丧失。这种效应在SCN中更明显，且在没有二价阳离子的情况下也是如此。0.1-4.0 mM Ca2+或Mg2+的存在部分且非选择性地逆转了这种由Na+引起的抑制作用。这些数据与已知的阳离子对激动剂与其他G蛋白偶联受体结合的影响一致，并加深了我们对哺乳动物MT受体的理解。
