大鼠神经病理性痛时脊髓mGluR4与SynapsinⅠ的关系

Relationship between spinal mGluR4 and SynapsinⅠin a rat model of neuropathic pain

目的评价大鼠神经病理性痛时脊髓代谢型谷氨酸受体4(mGluR4)与突触素Ⅰ(SynapsinⅠ)的关系。方法取鞘内置管成功的清洁级健康雄性SD大鼠40只,体重200~250 g,采用随机数字表法分为4组(n=10):对照组(Con组)、神经病理性痛组(NP组)、mGluR激动剂L-AP4组(L组)和mGluR4正性变构调节剂VU0155041组(VU组)。采用脊神经根结扎法制备大鼠神经病理性痛模型。造模后7 d行为学测试结束后,NP组、L组和VU组分别鞘内注射生理盐水10μl、L-AP4150 nmol(用生理盐水稀释至10μl)和VU0155041500 nmol(用生理盐水稀释至10μl),2次/d,连续7 d。于造模前、造模后7 d、鞘内给药第2、4、6和8天时测定机械缩足反应阈(MWT)。行为学测试结束后,每组取3只大鼠,采用Western blot法测定脊髓mGluR4和SynapsinⅠ的表达。结果与Con组比较,NP组、L组和VU组造模后7 d和鞘内给药各时点MWT降低,脊髓mGluR4表达下调,SynapsinⅠ表达上调(P<0.05或0.01)。与NP组比较,L组和VU组鞘内给药第4、6和8天时MWT升高,脊髓mGluR4表达上调,SynapsinⅠ表达下调(P<0.05)。L组和VU组上述各指标比较差异无统计学意义(P>0.05)。结论脊髓mGluR4表达下调可上调SynapsinⅠ的表达,参与大鼠神经病理性痛的形成。

Objective To evaluate the relationship between spinal metabotropic glutamate receptor 4(mGluR4)and SynapsinⅠin a rat model of neuropathic pain(NP).Methods Forty male Sprague-Dawley rats,weighing 200-250 g,in which intrathecal catheters were successfully implanted,were randomized into 4 groups(n=10 each)using a random number table method:control group(Con group),NP plus normal saline group(NP group),NP plus mGlu4 agonist L-AP4 group(L group),and an mGluR4-specific agonist VU0155041 group(VU group).The model of NP was established by spinal nerve ligation(SNL)in anesthetized rats.At the end of the behavioral test performed on day 7 after SNL,normal saline 10μl,L-AP4150 nmol(in normal saline 10μl)and VU0155041500 nmol(in normal saline 10μl)were intrathecally injected,twice a day,for 7 consecutive days,in NP group,L group and VU group,respectively.Mechanical paw withdrawal threshold was measured before SNL,at day 7 after SNL,and at days 2,4,6 and 8 after intrathecal administration.Three rats from each group were selected after the end of the behavioral test,and the expression of mGluR4 and SynapsinⅠin the spinal cord was determined by Western blot.Results Compared with Con group,MWT was significantly decreased on day 7 after SNL and at each time point after intrathecal administration in NP group,L group and VU group(P<0.05 or 0.01).Compared with NP group,MWT was significantly increased on 4,6 and 8 days after intrathecal injection,the mGluR4 expression was up-regulated,and the expression of SynapsinⅠwas down-regulated in L group and UV group(P<0.05).There was no significant difference in the above indicators between L group and VU group(P>0.05).Conclusion Down-regulation of mGluR4 expression in the spinal cord can up-regulate the expression of SynapsinⅠ,which is involved in the development of NP in rats.