Massicotte G, Kessler M, Lynch G, Baudry M
Center for the Neurobiology of Learning and Memory, University of California, Irvine 92717.
Mol Pharmacol. 1990 Feb;37(2):278-85.
The effect of phospholipase C (PLC) treatment of rat brain membranes on the binding properties of excitatory amino acid receptors was investigated using both a phosphsphatidylcholine-hydrolyzing PLC from Clostridium perfringens and a phosphatidylinositol-specific PLC from Bacillus thuringiensis. PLC from C. perfringens produced an increased affinity of the quisqualate/DL-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor for its ligand, whereas kainate receptor binding was not affected. Both kinetic analysis and equilibrium saturation experiments indicated that PLC treatment produced a decrease in affinity for [3H]N-(1-[thienyl]cyclohexyl)-piperidine [( 3H]TCP), a ligand for the N-methyl-D-aspartate (NMDA) receptor-associated ionic channel, when the channel was fully activated by high concentrations of glutamate and glycine but increased its binding under conditions in which the channel was presumably closed. This latter component of the binding was not due to an interaction of [3H]TCP with non-glutamate receptor sites, such as sigma opioid and histamine H3 receptors. Binding of [3H]glutamate and [3H] glycine to the NMDA receptors was not modified by PLC treatment, but there was a large decrease in the binding of the NMDA antagonist [3H]3-[(+/-)-2-carboxypiperazine-4-yl)propyl-1-phosphonic acid. Stimulation by glycine of [3H]glutamate binding was also abolished following PLC treatment. In contrast to PLC from C. perfringens, phosphatidylinositol-specific PLC treatment did not detectably modify the binding properties of the quisqualate/AMPA receptor or the NMDA receptor channel. These data indicate that alterations in the lipid microenvironment of the glutamate receptors modulate both the conformation and the function of the receptors and suggest a possible role for phospholipases in the regulation of synaptic transmission at excitatory synapses.
利用来自产气荚膜梭菌的磷脂酰胆碱水解性磷脂酶C（PLC）和来自苏云金芽孢杆菌的磷脂酰肌醇特异性PLC，研究了PLC处理大鼠脑膜对兴奋性氨基酸受体结合特性的影响。产气荚膜梭菌的PLC使quisqualate/DL-α-氨基-3-羟基-5-甲基异恶唑-4-丙酸（AMPA）受体对其配体的亲和力增加，而对海人藻酸受体结合没有影响。动力学分析和平衡饱和实验均表明，当通道被高浓度谷氨酸和甘氨酸完全激活时，PLC处理使N-甲基-D-天冬氨酸（NMDA）受体相关离子通道的配体[3H]N-（1-[噻吩基]环己基）-哌啶[（3H]TCP）的亲和力降低，但在通道可能关闭的条件下增加了其结合。结合的后一种成分不是由于[3H]TCP与非谷氨酸受体位点（如σ阿片受体和组胺H3受体）的相互作用。PLC处理未改变[3H]谷氨酸和[3H]甘氨酸与NMDA受体的结合，但NMDA拮抗剂[3H]3-[(±)-2-羧基哌嗪-4-基）丙基-1-膦酸的结合大幅减少。PLC处理后，甘氨酸对[3H]谷氨酸结合的刺激作用也被消除。与产气荚膜梭菌的PLC相反，磷脂酰肌醇特异性PLC处理未明显改变quisqualate/AMPA受体或NMDA受体通道的结合特性。这些数据表明，谷氨酸受体脂质微环境的改变调节了受体的构象和功能，并提示磷脂酶在兴奋性突触处的突触传递调节中可能发挥作用。
