Murzina G B, Sil'kis I G
Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow.
Neurosci Behav Physiol. 1998 Mar-Apr;28(2):121-9. doi: 10.1007/BF02461957.
A mathematical model of posttetanic processes launched by rhythmic stimulation of the excitatory and inhibitory inputs to the dendritic spine of a pyramidal neuron in hippocampal field CA3 was used to study conditions for modifying the efficiency of the inhibitory input. The level of dephosphorylation of GABAa and GABAb receptors, which determines the GABA sensitivity of these receptors, was shown to depend on the Ca(2+)-dependent ratio of active protein kinases and protein phosphatases; the level of dephosphorylation decreased monotonically as the intracellular Ca2+ increased. Posttetanic increases and decreases in the Ca2+ concentration, as compared with the level achieved during the previous stimulation, led to increases or decreases respectively in the number of dephosphorylated GABA receptors and to induction of long-term potentiation and depression, respectively, in the efficiency of inhibitory transmission. The extent of the modification effect depended on the ratio of the quantities of inhibitory and excitatory mediators in the synaptic cleft. At very low or very high GABA concentrations, modification of inhibitory transmission was insignificant.
利用一个数学模型研究了改变海马体CA3区锥体细胞树突棘兴奋性和抑制性输入节律性刺激引发的强直后过程中抑制性输入效率的条件。结果表明，决定GABA受体对GABA敏感性的GABAa和GABAb受体的去磷酸化水平取决于活性蛋白激酶和蛋白磷酸酶的钙依赖比例；随着细胞内Ca2+增加，去磷酸化水平单调下降。与前一次刺激期间达到的水平相比，强直后Ca2+浓度的升高和降低分别导致去磷酸化GABA受体数量的增加或减少，并分别诱导抑制性传递效率的长时程增强和长时程抑制。修饰作用的程度取决于突触间隙中抑制性和兴奋性介质数量的比例。在极低或极高的GABA浓度下，抑制性传递的修饰作用微不足道。
