Ⅰ组代谢型谷氨酸受体在帕金森病大鼠模型中的表达变化

Changes in expression of groupⅠmGluRs in a 6-OHDA model of Parkinson’s disease

目的通过研究Ⅰ组代谢型谷氨酸受体(mGluRs)mGluR1及mGluR5在帕金森病(PD)大鼠纹状体神经元细胞膜蛋白和总蛋白的表达变化,探讨Ⅰ组mGluRs在纹状体神经元细胞膜/细胞内分布改变是否参与PD的发病机制。方法选取雄性SD大鼠20只,随机分为PD组〔以6-羟多巴(6-OHDA)单侧脑内注射法制备;n=10〕和Sham组(操作方法相同,以等量生理盐水代替6-OHDA;n=10)。采用Western blot方法检测两组大鼠纹状体损伤侧和非损伤侧mGluR1及mGluR5总蛋白和膜蛋白水平变化,以及其下游重要信号分子细胞外信号调节激酶1/2(ERK1/2)和c-Jun氨基末端激酶(JNK)磷酸化水平,比较两组损伤侧与非损伤侧上述各指标表达情况。结果Western blot结果显示Sham组非损伤侧、Sham组损伤侧、PD组非损伤测及PD组损伤侧mGluR1总蛋白水平差异无统计学意义(F=0.329,P=0.805),PD组损伤侧mGluR1膜蛋白表达较PD组非损伤侧、Sham组损伤侧和Sham组非损伤侧均明显增高(均P<0.05);PD组损伤侧mGluR5总蛋白水平和膜蛋白水平均较相应PD组非损伤侧、Sham组损伤侧及Sham组非损伤侧均明显增高(均P<0.05);与PD组非损伤侧、Sham组损伤侧和Sham组非损伤侧比较,PD组损伤侧ERK1/2磷酸化水平明显降低,JNK磷酸化水平明显升高(均P<0.05);上述指标在PD组非损伤侧、Sham组损伤侧和Sham组非损伤侧之间两两比较差异均无统计学意义(均P>0.05)。结论PD大鼠纹状体Ⅰ组mGluRs的变化以膜蛋白的表达异常增加为主,可能与其在细胞膜/细胞内分布的改变相关,并且改变可能影响下游ERK1/2和JNK磷酸化水平,推测纹状体神经元Ⅰ组mGluRs分布的变化可能与PD发病机制相关。

Objective To explore whether the change of the striatal neuron membrane/intracellular distribution of groupⅠmetabotropic glutamate receptors(mGluRs)is involved in the pathogenesis of Parkinson’s disease(PD),by studying the alternation of mGluRs membrane-protein and total protein expression in the striatum of PD rat model.Methods Twenty male SD rats were randomly divided into a PD group(prepared by unilateral intracerebral injection of 6-OHDA;n=10)and a sham group(prepared by the same method,with the same amount of saline instead of 6-OHDA;n=10).Western blot method was used to detect changes of the total protein and membrane protein expression of mGluR1 and mGluR5,in the lesion and non-lesion sides of the two groups,as well as the phosphorylation levels of extracellular signal-regulated kinases 1/2(ERK1/2)and c-Jun N-terminal kinase(JNK)which are important signal molecules downstream of mGluR1 and mGluR5.The expressions of these proteins in lesion and non-lesion sides were compared between the two groups.Results The data showed that the total expression of mGluR1 in non-lesion sides of the sham group,lesion side of the sham group,non-lesion side of the PD group and the lesion side of the PD group were not significantly different(F=0.329,P=0.805).The membrane-expression of mGluR1 in the lesion side of the PD group was significantly higher than the non-lesion side of the PD group,lesion side of the sham group,and non-lesion side of the sham group(P<0.05,respectively).Both total expression and membrane-expression of mGluR5 in the lesion side of the PD group were significantly higher than those in the non-lesion side,lesion side of the sham group,and non-lesion side of the sham group(P<0.05,respectively).Compared with unlesion side of the PD group,lesion side of the sham group,and non-lesion side of the sham group,the phosphorylation level of ERK1/2 in the lesion side of the PD group was significantly decreased,while the phosphorylation level of JNK was significantly increased(P<0.05,respectively).Conclusions The changes of groupⅠmGluRs in the striatum of PD rat model are mainly the significant increase of its membrane protein expression,which may be related to the changes of its cell membrane/intracellular distribution.These changes might affect the phosphorylation levels of downstream ERK1/2 and JNK.These data suggest that the changes of striatal subcellular distribution of groupⅠmGluRs may be involved in the pathogenesis of PD.