Saito M, Serikyaku S, Ishitani R
Group of Neuropharmacology, Josai University, Saitama, Japan.
Jpn J Pharmacol. 1991 Aug;56(4):413-9. doi: 10.1254/jjp.56.413.
To investigate a link between membrane phospholipids and tryptamine binding molecules, we examined the effects of phospholipases A2 and D on the temperature-sensitive high-affinity [3H]tryptamine binding sites in rat brain. When the phospholipase A2-treated membranes were exposed to 1% bovine serum albumin (BSA) before assaying for [3H]tryptamine binding, a complete dose-dependent inhibition curve was observed. At a concentration of 0.03 U, the action of phospholipase A2 resulted in the splitting of phosphatidylserine (PS), choline phosphatides (PC) and ethanolamine phosphatides (PE) by about 32, 34 and 65%, respectively, and reduced [3H]ligand binding by about 32%. On the contrary, in the case of phospholipase D (500 U), PS and PC decreased by about 8% and 33% and PE by about 29% with no significant alteration in the binding capacity. Moreover, Scatchard analysis of the [3H]tryptamine binding showed that phospholipase A2 drastically increased only the KD value of the high affinity sites, and this was accompanied by a decrement of the Bmax values of both the high and low affinity binding sites. From these results, it is inferred that certain lipids (PS) may be a modulator for the function of the temperature-induced high-affinity [3H]tryptamine binding molecules.
为了研究膜磷脂与色胺结合分子之间的联系，我们检测了磷脂酶A2和磷脂酶D对大鼠脑中温度敏感型高亲和力[3H]色胺结合位点的影响。在测定[3H]色胺结合之前，将经磷脂酶A2处理的膜暴露于1%牛血清白蛋白（BSA）中，观察到了完整的剂量依赖性抑制曲线。在浓度为0.03 U时，磷脂酶A2的作用分别导致磷脂酰丝氨酸（PS）、胆碱磷脂（PC）和乙醇胺磷脂（PE）的分解约32%、34%和65%，并使[3H]配体结合减少约32%。相反，对于磷脂酶D（500 U），PS和PC分别下降约8%和33%，PE下降约29%，结合能力无显著变化。此外，对[3H]色胺结合的Scatchard分析表明，磷脂酶A2仅显著增加高亲和力位点的KD值，同时伴随着高亲和力和低亲和力结合位点的Bmax值下降。从这些结果可以推断，某些脂质（PS）可能是温度诱导的高亲和力[3H]色胺结合分子功能的调节剂。
