黑皮质素受体-4在癫痫模型大鼠脑组织中的表达及相关机制

Altered expression of melanocortin-4 receptor in brain tissue of mouse epilepsy model

目的探讨黑皮质素受体-4(melanocortin-4 receptor,MC4R)在癫痫模型大鼠脑组织中的表达及可能的相关机制。方法将52只雄性SD大鼠分为对照组,6、24、72 h、7、14、30、60 d 8个实验组,实验组建立氯化锂-匹罗卡品模型,采用Western blot、免疫组织化学、免疫组织荧光法检测MC4R在模型大鼠脑组织中的表达及分布。另外40只雄性SD大鼠,分成正常对照组、戊四氮组(pentylenetetrazol,PTZ)、PTZ+0.9%Na Cl组和PTZ+HS014组(HS014为MC4R特异性抑制剂),建立PTZ慢性点燃模型,记录各组发作情况。建模28 d后将各组大鼠处死,Western blot检测各组大鼠PhspoGluR1(Ser 845)的表达情况。结果与对照组相比,MC4R在氯化锂-匹罗卡品模型大鼠脑组织中呈动态升高趋势,并于第14天达峰值(P<0.01)。在PTZ慢性点燃过程中,与对照相比,经HS014干预大鼠的平均发作评分明显降低(P<0.05),全身强直阵挛发作(generalized tonic-clonicseizure,GTCS)的潜伏期明显延长(P<0.05)。29 d后Western blot检测结果显示HS014处理组大鼠脑组织中的Phspo-GluR1(ser845)表达量较PTZ组明显下降(P<0.05)。结论 MCR4可能通过调节GluR1的ser 845位点的磷酸化水平参与到了癫痫的发生、发展中。

Objective To determine the effect of melanocortin-4 receptor（MC4R） on the epileptogenesis and to discover the potential mechanism involved.Methods Fifty-two male SD rats were divided into a control group and 7 experimental groups（6,24 and 72 h,7,14,30 and 60 d）.Western bloting,immunohistochemistry,and double-labelled immunofluorescence assay were then applied to detect the dynamic change of the expression pattern of MC4 R in the brain tissue of the pilocarpine kindled rats.Forty male SD rats were then divided into the control,pentylenetetrazol（PTZ）,PTZ ＋ 0.9% Na Cl,and PTZ ＋ 0.9% Na Cl＋ HS014（a specific inhibitor to MC4R） groups.The sub-convulsion dosage of PTZ was applied every other day for 29 d to establish the chronically kindled models and observe the kindling scores,and the latency and duration of generalized tonic-clonic seizure（GTCS） of each group.All animals were sacrificed on the 28 th day after the models were established,and the expression of phspo-GluR1（Ser 845） in the brain tissue of the rats in each group was detected by Western blotting.Results The MC4 R expression was significantly increased in the brain tissue of the pilocarpine kindled rats at each time point as compared with the control group（P 〈0.05）,and the peak occurred on the 14 th day（P 〈 0.01）.The MC4 R inhibitor HS014 significantly decreased the kindling scores（P 〈 0.05） and prolonged the onset latency（P 〈 0.05） of GTCS in the rats during the PTZ chronic kindling process.The expression of phspo-GluR1（Ser 845） of the HS014 treated group was decreased as compared with the PTZ group（P 〈 0.05）.Conclusion Over-expression of MC4 R might participate in the process of epileptogenesis via facilitating the phosphorylation process of GluR1（Ser 845）.