腺苷A1受体和NMDA受体在海马齿状回突触传递活动中的关系

目的　探讨腺苷A1受体阻断剂对海马齿状回 (DG)突触传递活动的影响及其与NMDA受体的关系。方法采用在体记录麻醉大鼠LTP的电生理学方法 ,观察腺苷A1受体特异性阻断剂 8 环戊 1,3 二丙基黄嘌呤 (DPCPX)与NMDA受体激动剂、阻断剂在海马DG基础突触传递活动和高频刺激诱导的LTP中作用的相关性。结果　DPCPX(6mg·L- 1,5μL ,icv)或NMDA(0 2mg·L- 1,5μL ,icv)不影响大鼠海马DG突触传递活动 ,DPCPX对icvNMDA后高频刺激诱导已形成的LTP维持也无影响 ;预先给予DPCPX后则可显著增强NMDA的海马DG基础突触传递活动和LTP ;AP5(0 5mg·L- 1,5μL)阻断NMDA受体后对LTP的抑制作用不受DPCPX的影响 ,但预先给予DPCPX则可取消AP5 对LTP的抑制作用。结论　DPCPX不影响海马DG突触传递活动 ,但可影响NMDA受体的效应 ,增强NMDA受体在海马DG突触传递活动中的作用

Relation between adenosine A1 receptor and NMDA receptor on synaptic transmission in dentate gyrus of hippocampus

AIM: To observe the effect of adenosine A, receptor antagonist on synaptic transmission in the dentate gyrus of hippocampus and its relations with NMDA receptor. METHODS: Using electrophysiological technique to record the long-term potentiation (LTP), the relation between selective adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and NMDA receptor agonist/antagonist, in both basic synaptic transmission and 200 Hz high-frequency stimulation (HFS) induced LTP of the dentate gyrus of hippocampus in anesthetized rats, was studied. RESULTS: DPCPX (6 mg x L(-1), 5 microL, icv) or NMDA (0.2 mg x L(-1), 5 microL, icv) was shown not to affect the synaptic transmission in the dentate gyrus in rats. DPCPX was found not to affect the keeping of LTP induced by HFS after icv NMDA. But the basic synaptic transmission and the magnitude of LTP induced by HFS in the dentate gyrus after icv NMDA could be enhanced significantly by icv DPCPX in advance. DPCPX could not affect the magnitude of LTP inhibited by AP5 (0.5 mg x L(-1), 5 microL) NMDA receptor antagonist, but the inhibitory effect of AP5 on LTP could be antagonized by icv DPCPX in advance. CONCLUSION: The selective adenosine A1 receptor antagonist DPCPX could not affect the synaptic transmission in the dentate gyrus of hippocampus, but could significantly enhance the effect of NMDA receptor in both basic synaptic transmission and HFS induced LTP in the dentate gyrus of hippocampus in anesthetized rats.