大鼠不同脑区微量注射蝇蕈醇与氯苯氨丁酸镇痛作用比较

Comparised the Analgesia Effects of Muscimol and Baclofen Microinjected in Different Brain Regions of Rats

目的观察并比较GABAa受体激动剂蝇蕈醇及GABAb受体激动剂氯苯氨丁酸在大鼠不同脑区的镇痛作用。方法实验分侧脑室、室旁核和海马三组 ,每组又分成生理盐水对照组、蝇蕈醇组及氯苯氨丁酸组 ,分别经侧脑室、海马和室旁核”微量注射生理盐水或药物 ( 1× 1 0 - 3 mol·L- 1,1 μl) ,在大鼠甩尾测痛模型上”测定大鼠的痛阈。结果微量注射蝇蕈醇和氯苯氨丁酸在不同脑区均可不同程度地提高大鼠的痛阈 (与生理盐水对照组相比 ,P <0 .0 5或P <0 .0 1或P <0 .0 0 1 ) ,虽然蝇蕈醇与氯苯氨丁酸在侧脑室和室旁核的镇痛作用无显著性差异 (P >0 .0 5 ) ,但氯苯氨丁酸在海马的镇痛作用明显强于蝇蕈醇(P <0 .0 0 1 )。比较药物在不同脑区的镇痛作用发现 ,氯苯氨丁酸在海马和室旁核的镇痛作用无明显区别 ,但均强于侧脑室 ;而蝇蕈醇在室旁核最强 ,其次为海马、侧脑室。结论经侧脑室、海马或室旁核微量注射蝇蕈醇或氯苯氨丁酸均能降低大鼠对痛的感受性。氯苯氨丁酸在海马和室旁核可产生较强的镇痛作用 ,而蝇蕈醇在室旁核镇痛作用较明显 。

Objective The present study was to investigate the analgesia effects of muscimol(Mus,a GABAa receptor agonist)and baclofen(Bac,a GABAb receptor agonist)microinjected in different brain regions of rats.Methods The study was divided into three groups according to the region of injection:intracerebroventricular(Icv),hippocampus(Hip)amd paraventricular(Par),and each group was divided into three subgroups:salt(control),Mus and Bac.The salt,Mus and Bac was microinjected(1μl) in Icv,Hip and Par respectively.The pain threshole(PT) was determined using tail flick test.Results Mus and Bac obviously raised the PT(P&lt;0.05 or P&lt;0.01 or P&lt;0.001 vs salt control).The analgesia effect of Bac was stronger than Mus in Hip,but they hadn’t marked difference in Icv of Par(P&gt;0.05).Compared in defferent brain regions,although the analgesia effect of the Bac in Hip hadn’t obviously different from Par,but they were very clear compared with Icv(P&lt;0.001). The analgesia ffect of the Mus was the strongest in Par,next in Hip and in Icv.Conclusion These observations suggest that Mus and Bac can decrease the rat’s pain sensitivity.The Bac has obvious analgesia effect when it is injected in Hip and Par,and the Mus has evident analgesia efficacy in Par.