东莨菪碱、印防己毒素对习得性长时程突触增强的影响

EFFECT OF SCOPOLAMINE AND PICROTOXIN ON THE LEARNING-DEPENDENT LONG-TERM SYNAPTIC POTENTIATION

在大鼠条件性饮水反应的建立、消退和再建立过程中,于海马 CA_3区记录电极部位微量注射 M-胆碱受体阻断剂东莨菪碱和 GABA 受体阻断剂印防已毒素,观察其对习得性长时程突触增强的影响。结果表明,东莨菪碱有明显的抑制作用,印防已毒素则有明显的易化作用,同时相应地影响条件性行为;并发现习得性长时程突触增强的发展与变化是超前于条件性行为的发展和改变的。上述结果为进一步论证习得性长时程突触增强可能是学习和记忆的神经基础之一提供了证据,并提示海马 CA_3区习得性长时程增强的产生与保持有胆碱受体与 GABA 受体参与。

The purpose of this study was to investigate the effects of microinjection ofscopolamine,a M-cholinergic antagonist and picrotoxin,a GABA-ergic antagonistinto the rat hippocampal CA_3 area on the learning-dependent long-term potenti-ation(LDLTP)during the establishment,extinction and re-establishment ofconditioned drinking response.Following stimulation of the perforant path,field potentials of hippocampal CA_3 of freely moving rats were recorded.The re-sults were as follows:the synaptic efficacy and the development of LDLTP in hip-pocampal CA_3 were depressed significantly by scopolamine,but the extinction ofLDLTP was accelerated.Picrotoxin significantly enhanced synaptic efficacy andfacilitated the development of LDLTP,but it depressed the extinction of LDLTP.Meanwhile,the establishment or extinction of drinking conditioning was corres-pondingly depressed or accelerated.Moreover,the development of LDLTP andits extinction preceded the development and extinction of drinking conditioning.The results provide further evidence indicating that LDLTP might be one ofthe neuronal mechanisms underlying behavioral learning and memory.Mo-reover,it seems that M-cholinergic receptors and GABA-ergic receptors in rathippocampal CA_3 area are involved in the development and retention of LDLTP.