蝎毒对C57BL/6帕金森病小鼠脑内前脑啡肽原表达的影响

Effect of scorpion venom on the expression of proenkephalin in C57BL/6 mice with Parkinson disease

目的:观察蝎毒对C57BL/6帕金森病小鼠运动协调与空间学习记忆能力以及脑内前脑啡肽原表达的影响。方法:实验于2004-03/06在大连医科大学生理学教研室进行。将96只C57BL/6小鼠随机分为模型组、模型给药组、单独给药组、盐水对照组,每组24只。模型组为连续8d皮下注射1-甲基-4-苯基-1,2,3,6-四氢吡啶(20mg/kg);模型给药和单独给药组给予蝎毒耐热蛋白连续8d,盐水对照组给等量生理盐水。测定爬杆、游泳实验评价运动协调能力。Morris水迷宫实验观察空间学习记忆能力。免疫细胞化学观察脑内多巴胺能神经元数目,反转录-聚合酶链反应测试脑内前脑啡肽mRNA改变。结果:96只小鼠均进入结果分析。①模型组小鼠的爬竿时间较盐水对照组、单独给药组延长,因此测试分数降低,出现运动障碍。模型给药组与模型组相比运动协调性障碍明显减轻(P<0.01)。模型组小鼠的游泳实验测试分数较盐水对照组降低,游泳能力降低,出现运动障碍。模型给药组与模型组相比运动障碍明显减轻(P<0.01)。②模型组小鼠寻找隐匿平台潜伏期明显比盐水对照组延长,盐水对照组小鼠空间学习能力下降。治疗组与模型组相比寻找隐匿平台潜伏期明显变短(P<0.01)。模型组小鼠于第5天在目标象限游泳时间占总时间百分比明显比盐水对照组降低,在对侧象限游泳时间占总时间百分比明显比盐水对照组增高(P<0.01)。模型组小鼠空间记忆能力下降。模型给药组与模型组相比有明显的改善(P<0.01)。③与盐水对照组相比,模型组小鼠黑质致密部的TH免疫反应阳性多巴胺能神经元明显脱失。模型给药组与模型组相比TH免疫反应阳性多巴胺能神经元数目明显增加(P<0.01)。④与盐水对照组相比,模型组小鼠脑区前脑啡肽原mRNA表达明显增强(P<0.05)。模型给药组与模型组相比前脑啡肽原mRNA表达明显降低(P<0.05)。结论:蝎毒保护中脑黑质致密部多巴胺能神经元并改善1-甲基-4-苯基-1,2,3,6-四氢吡啶引起的运动协调性降低和空间学习记忆障碍,其保护机制可能与降低异常的前脑啡肽原表达有关。

AIM： To observe the effect of the scorpion venom on the locomotor harmony, spatial learning memory, and the expression of proenkephain （PENK） in Parkinson disease animal model in C57BL/6 mice. METHODS： The experiment was performed from March to June 2004 at the Department of Physiology in Dalian Medical University. C57BL/6 mice （n=96） were divided into four groups randomly： model group, therapy group, scorpion venom treated control group, saline treated control group with 24 mice in each group. The mice in the model group were injected with 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine （MPTP） （20 mg/kg） subcutaneously for 8 days. Those in the scorpion venom treated control group and therapy group were treated with scorpion venom for 8 days. Those in the saline treated group were given the same volume of saline. Pole and swim tests were used to measure the locomotor harmony. Morris water maze was performed for analyzing the spatial learning memory ability. Immunocytochemistry and reverse transcription-polymerase chain reaction （RT-PCR） were used to detect the number of dopaminergic neurons and the expression of PENK mRNA in the brain, respectively. RESULTS： A total of 96 mice were involved in the result anlaysis. ① The duration of pole in the model group was prolonged as compared with the saline treated control groupscorpion venom treated control group, so the score was lower, while motor disturbance was occurred. The disturbance of motor coordination was obviously lightened in the therapy group as compared with the model group （P 〈 0.01 ）. The score of swimming test in model group decreased as compared to the saline treated control group, and the ability of swimming declined, and the motor disturbance was occurred. The disturbance of motor coordination was Obviously lightened in the therapy group as compared with the model group （P 〈 0.01 ）. ②The search latency of mice in the model group was significantly longer than that of the saline treated control group. The spatial learning memory decreased in the saline treated control group. The search latency of mice in therapy group and the model group was obviously shorten （P 〈 0.01 ）. The percentage of objective quadrant swimming time to total time at day 5 in the model group markedly decreased as compared with the saline treated control group, while the percentage of quadrant swimming time at the opposite side to total time remarkably increased as compared with the saline treated control group （P 〈 0.01 ）. The spatial learning memory ability in the model group reduced. The therapy group was distinctly improved as compared with the model group （P 〈 0.01）. ③Compared with the saline treated control group, there was large loss of tyrosine hydroxylase （TH）-IR positive neurons in substantia nigra compact in the model group. The number of TH-IR positive neurons in the therapy group dramatically increased as compared with the model group （P 〈 0.01 ）. ④Compared with the saline treated contrel group, the expression of PENK mRNA in the encephalic region of mice of the model group significantly increased （P〈0.05）. The expression of PENK mRNA obviously reduced in the therapy group as compared with the model group （P 〈 0.05 ）. CONCLUSION： The scorpion venom protects dopaminergie neurons of substantia nigra compact region of midbrain, ameliorates the locomotor disability and spatial learning memory deficits induced by MPTP, and its protective mechanism may be associated with the decreasing of the abnormal expression of PENK.