褪黑素对谷氨酸致痫大鼠海马内谷氨酸、GABA及其受体水平的影响

EFFECTS OF MELATONIN ON LEVELS OF GLUTAMATE,GABA AND THEIR RECEPTORS IN THE HIPPOCAMPUS OF RATS WITH SEIZURES INDUCED BY GLUTAMATE

目的探讨褪黑素(melatonin,MT)对谷氨酸(glutamate,Glu)致痫大鼠海马内Glu及GluR2、γ-氨基丁酸(γ-aminobutyric-acid,GABA)及其受体GABRA1水平的影响,进而研究褪黑素的抑痫作用机制。方法随机将健康SD雄性大鼠40只分为A、B、C、D组,每组10只。A组:生理盐水组;B组:MT+Glu组;C组:Glu致痫组;D组:Luzidole+MT+Glu组。观察并记录行为学变化,采用免疫组化法进行Glu、GluR2、GABA和GABRA1免疫组化染色和图像分析。结果行为学观察结果显示,C组和D组大鼠均有不同程度的癫痫发作,B组大鼠癫痫发作不明显,A组无发作;免疫组化结果显示,C组和D组海马内CA1-CA3区和齿状回Glu阳性反应较A组增强(P<0.05),GluR2、GABA和GABRA1均较A组减弱(P<0.05),B组Glu较C组和D组阳性反应有显著性减弱(P<0.05),GluR2、GABA和GABRA1阳性反应均较C组和D组有显著性增强(P<0.05),而B组与A组无明显差异性。结论MT通过增加GABA及其受体GABRA1和GluR2的作用和抑制Glu作用对Glu致痫大鼠癫痫发作发挥抑制作用。

Objective To investigate the mechanism of melatonin （MT） in preventing ITGlu-induced seizures by studying its effect on glutamate （Glu）, GluR2, 7-aminobutyrie-acid （GABA） , and GABRA1 in rat hippocampus. Methods Forty healthy male Sprague-Dawley （SD） rats were randomly divided into A, B, C and D groups, of 10 each. Rats of group A were given intracerebroventricularly （i. c. v. ） normal saline. Rats of group B were injected with MT intraperitoneally （i. p. ） and L-Glu i. c. v. Rats of group C were injected with ITGlu i. c. v, and rats of group D were given luzidole i. c. v. , MT i. p. and L-Glu i. c. v. The behavior of the rats was observed, and immunohistochemical staining was performed to evaluate the changes of Glu, GluR2, GABA, GABRA1 in each group. Results The behavior of the animals in both group C and D showed epileptic convulsions and electric discharge, while the other groups did not. The immunohistochemical staining showed that Glu, GluR2, GABA and GABRA1 existed in the CA1-CA3 area and dentate gyrus of the hippocampus. The mean optical dentity （OD） of Glu positive immunoreaction in group C and D was obviously stronger than that of group A and B （P〈0.05）, whereas the mean optical dentity （OD） of GABA, GABRA1 and GluR2 positive immunoreaction in group C and D was obviously weaker than that of group A and B （P〈0. 05）. The results of group A and t5 had no obvious difference. Conclusion MT may prevent the seizure induced by L- Glu in rats by increasing the expression of GABA, GABRA1 and GluR2 and inhibiting the expression of Glu.