降钙素基因相关肽对低氧下海马脑片突触功能的保护作用

PROTECTIVE EFFECT OF CALCITONIN GENE-RELATED PEPTIDE ON SYNAPTIC FUNCTION IN HIPPOCAMPAL SLICE DURING HYPOXIA

本文采用大鼠海马脑薄片，同时双通道记录脑片的诱发电位，观察低氧下突触功能的变化，并于一侧脑片灌流降钙素基因相关肽（ＣＧＲＰ），另侧作对照，比较双孔脑片诱发电位的异同。结果显示，电刺激ＣＡ３区的Ｓｃｈａｆｆｅｒ侧支，可在ＣＡ１区锥体细胞诱发突触前排放（ＰＶ）和突触后群峰电位（ＰＳ）。低氧时ＰＳ迅速减小并逐渐消失。部分脑片出现低氧损伤电位（ＨＩＰ）。经ＣＧＲＰ灌流的脑片低氧后电位开始减小与完全消失的时间均向后推迟，ＨＩＰ出现减少或延迟。恢复给氧后，ＣＧＲＰ组脑片恢复率明显高于对照组，呈现剂量依赖性保护作用。此外，低氧后给予ＣＧＲＰ亦可提高突触功能恢复率。以上结果提示低氧早期海马突触功能迅速受损，神经肽－ＣＧＲＰ对此具有明显的保护作用。

Rat hippocampal slices placed In two compartments of a dual chamber were im mersed in the sunerfusins artificial cerebrosPinal fluid(ACSF)with 95% O2+5%COZ.The population spike(PS)and presynaptic fiber volley(PV)were recorded In CAI pyramidal cells by stimulating Schaffer collateral pathways.Following hypoxla PtodllCCd by replacing O2 With N2,the PS became gradually diminished and abolished,and In parts of the sliceshypoxic injury spikes(HIP)could be observed.When 4nmol/L β-calcitonin gene-related peptide(CGRP)-containing ACSF was superfused to the slice before and during hypoxia,the time at which PS began to decrease and got In cottiplete eabohshttientwele both postponed,and HIPWere ddayed ot disappeared.After reoxygenatlon the recovery rate of PS was obviously higher in slices treated with CGRP than the control slices and the protective effect of CGRP was dose-dependent.In addition,superfusion of CGRP after hypoxia also Increased the recovery of PS.These results indicate that(1)the time for the appearance of attenuation and dlsappearence of PS are varied according to the degree of hypoxia;(2)CGRP has a neuronal protective action against hypoxla.