Chakravarthy B R, Wang J, Tremblay R, Atkinson T G, Wang F, Li H, Buchan A M, Durkin J P
Institute for Biological Sciences, National Research Council of Canada, Ottawa, Canada.
Cell Signal. 1998 Apr;10(4):291-5. doi: 10.1016/s0898-6568(97)00131-9.
Changes in protein kinase C (PKC) were compared in primary cortical neurons exposed to glutamate and in the CA-1 hippocampal region of rats subjected to transient cerebral ischaemia. After a 15-min exposure of cortical neurons to excitotoxic levels of glutamate, a 50-60% loss of membrane PKC activity but only about a 20% loss in the amount of enzyme was observed, suggesting that in addition to enzyme loss other mechanisms also contributed to the overall loss of membrane PKC activity. Glutamate induced a 25-40% decrease in immunodetectable levels of PKC alpha, beta, gamma, and lambda but no detectable changes in PCK epsilon and zeta. The loss of PKC activity coincided with a shift in electrophoretic mobility of PKC gamma, epsilon, and lambda, but not of PKC alpha, beta, or zeta, suggesting post-translational modification of some PKC isoforms. By comparison, in rats subjected to transient (15-min) global ischaemia, a similar 50-60% decrease in membrane PKC activity, a 20-25% loss in the amount of PKC, and a shift in PKC mobility were observed in CA-1 neurons 6 h post-reperfusion. In both the in vivo and the in vitro "ischaemic" models, administration of the AMPA receptor antagonist NBQX prevented the loss of PKC activity. These results indicate that the loss of PKC observed in in vivo ischaemia is likely to be due to excitotoxic damage and that this event can be closely mirrored in primary neuronal cultures damaged by glutamate.
比较了暴露于谷氨酸的原代皮质神经元和短暂性脑缺血大鼠海马CA-1区蛋白激酶C（PKC）的变化。在皮质神经元暴露于兴奋性毒性水平的谷氨酸15分钟后，观察到膜PKC活性丧失50 - 60%，但酶量仅损失约20%，这表明除了酶的损失外，其他机制也导致了膜PKC活性的总体丧失。谷氨酸使可免疫检测到的PKCα、β、γ和λ水平降低25 - 40%，但未检测到PCKε和ζ的变化。PKC活性的丧失与PKCγ、ε和λ的电泳迁移率改变一致，但PKCα、β或ζ未出现此变化，提示一些PKC同工型发生了翻译后修饰。相比之下，在短暂性（15分钟）全脑缺血的大鼠中，再灌注6小时后，CA-1神经元中膜PKC活性同样降低了50 - 60%，PKC量损失了20 - 25%，且PKC迁移率发生改变。在体内和体外“缺血”模型中，给予AMPA受体拮抗剂NBQX均可防止PKC活性丧失。这些结果表明，在体内缺血中观察到的PKC丧失可能是由于兴奋性毒性损伤所致，并且这一事件在受谷氨酸损伤的原代神经元培养物中可得到密切反映。
