Niles L P
J Pineal Res. 1987;4(1):89-98. doi: 10.1111/j.1600-079x.1987.tb00844.x.
The binding characteristics of the tritiated pineal hormone, [3H] melatonin, were studied in brain tissues using in vitro binding techniques. In synaptosomal membranes prepared from rat hippocampus and subjected to preincubation at 37 degrees C and multiple washings, high-affinity binding of [3H] melatonin significantly exceeds that previously reported for membrane or cytosol fractions from mammalian brain. Scatchard analysis of saturation binding data indicates that binding affinities are similar in membrane (Kd = 15 nM) and cytosol (Kd = 11 nM) preparations. However, binding is about sevenfold greater in membranes than in cytosol prepared by centrifugation of homogenates at 104,000g for 60 min. Specific binding is also present in both particulate and soluble fractions from calf brain. Inhibition experiments, in rat hippocampal membranes, indicate that norepinephrine is the most potent inhibitor of about 55% of total binding. Serotonin also exhibited high affinity for about 25% of total binding, suggesting that [3H] melatonin labels both adrenergic and serotonergic sites in this brain region. Further studies are required to characterize the serotonergic and adrenergic sites labelled by [3H] melatonin and to determine whether these sites are functionally important receptors for melatonin.
利用体外结合技术，研究了氚标记的松果体激素[3H]褪黑素在脑组织中的结合特性。在从大鼠海马体制备的突触体膜中，于37℃进行预孵育并多次洗涤后，[3H]褪黑素的高亲和力结合显著超过先前报道的哺乳动物脑的膜或胞质溶胶部分的结合。对饱和结合数据的Scatchard分析表明，膜制剂（Kd = 15 nM）和胞质溶胶制剂（Kd = 11 nM）中的结合亲和力相似。然而，通过在104,000g下将匀浆离心60分钟制备的膜中的结合比胞质溶胶中的结合大约高7倍。小牛脑的颗粒和可溶性部分中也存在特异性结合。在大鼠海马体膜中的抑制实验表明，去甲肾上腺素是约55%总结合的最有效抑制剂。5-羟色胺对约25%的总结合也表现出高亲和力，这表明[3H]褪黑素在该脑区标记了肾上腺素能和5-羟色胺能位点。需要进一步研究以表征由[3H]褪黑素标记的5-羟色胺能和肾上腺素能位点，并确定这些位点是否是褪黑素的功能重要受体。
