Lee M, Strahlendorf H K, Strahlendorf J C
Department of Physiology, Texas Tech University Health Sciences Center, Lubbock 79430.
Brain Res. 1988 Jul 19;456(1):104-12. doi: 10.1016/0006-8993(88)90351-4.
The effects of N-methyl-D-aspartic acid (NMDA) and L-homocysteic acid (LH) were measured on cerebellar Purkinje neurons. In urethane-anesthetized rats, iontophoretic application of NMDA elicited 3 different effects on the spontaneous activity of Purkinje cells: excitation, inhibition and biphasic responses consisting of excitation followed by inhibition. On the other hand, LH elicited excitation, only, regardless of the actions of NMDA on the same neurons. We also examined the effects of various excitatory amino acid antagonists on NMDA- and LH-mediated responses. Excitatory effects of NMDA were antagonized effectively by D.L-2-amino-5-phosphonovalerate (APV), ketamine, gamma-D-glutamylglycine (DGG), D,L-2-amino-7-phosphonoheptanoate (APH), and were not influenced significantly by L-glutamate diethylester (GDEE). Inhibitory responses of NMDA were antagonized by APV, APH and ketamine. LH-mediated excitations were influenced significantly by DGG and ketamine whereas GDEE, APV and APH failed significantly to attenuate the effects of LH. Based on the differential actions of LH and NMDA and the selectivity of NMDA antagonists for NMDA rather than LH-mediated excitations, it appears that the major actions of LH may not be mediated through NMDA receptor sites, at least in the cerebellum.
研究了N-甲基-D-天冬氨酸（NMDA）和L-高半胱氨酸（LH）对小脑浦肯野神经元的作用。在氨基甲酸乙酯麻醉的大鼠中，离子导入NMDA对浦肯野细胞的自发活动产生3种不同的作用：兴奋、抑制以及先兴奋后抑制的双相反应。另一方面，无论NMDA对同一神经元有何作用，LH仅引起兴奋。我们还研究了各种兴奋性氨基酸拮抗剂对NMDA和LH介导反应的影响。NMDA的兴奋作用可被D,L-2-氨基-5-磷酸戊酸（APV）、氯胺酮、γ-D-谷氨酰甘氨酸（DGG）、D,L-2-氨基-7-磷酸庚酸（APH）有效拮抗，而L-谷氨酸二乙酯（GDEE）对其无显著影响。NMDA的抑制反应可被APV、APH和氯胺酮拮抗。DGG和氯胺酮对LH介导的兴奋有显著影响，而GDEE、APV和APH则不能显著减弱LH的作用。基于LH和NMDA的不同作用以及NMDA拮抗剂对NMDA介导而非LH介导兴奋的选择性，至少在小脑中，LH的主要作用似乎不是通过NMDA受体位点介导的。
