经侧脑室注射脂多糖诱导大鼠黑质部位小胶质细胞激活及多巴胺能神经元损伤的研究

Activation of microglia and dopaminergic neurons degeneration following intraventricular injection of LPS in the substantia nigra of rats

目的观察经脑室注射脂多糖(LPS)后大鼠的黑质部小胶质细胞激活及多巴胺(DA)能神经元的变化,探讨脑内炎性反应在黑质DA能神经元慢性变性过程中的作用。方法健康雄性SD大鼠30只,随机分为生理盐水(NS)对照组和LPS组,分别向大鼠右侧脑室注射20μL NS或50μg LPS,40周后用免疫组织化学方法检测大鼠黑质小胶质细胞是否激活、激活的程度(OX-42及OX-6抗体水平),以及酪氨酸羟化酶(TH)阳性神经元的形态和数量。以Fluoro-Jade B(FJB)染色法检测黑质部位神经元变性情况。结果 (1)NS对照组大鼠黑质部位OX-42阳性小胶质细胞呈静息状态,染色浅。LPS组大鼠黑质部OX-42阳性小胶质细胞呈部分激活状态,染色深。两组大鼠黑质部位均未发现OX-6阳性小胶质细胞。(2)NS对照组大鼠黑质部位有大量深染的TH阳性神经元。LPS组大鼠黑质部位TH阳性染色神经元数目(99.11±20.31)比NS对照组(189.52±12.12)减少47.7%(P<0.01)。(3)两组大鼠黑质部位均未见FJB阳性染色神经元。结论经侧脑室单次注射LPS可能造成大鼠黑质部位小胶质细胞长期慢性激活及DA能神经元慢性迟发性功能性损伤。

Objective To investigate the effect of intraventricular injection of lipoplysaccharide（LPS） on microglia activation and dopaminergic（DA） neurons in the substantia nigra of rats and to explore the role of intracephalic inflammation on DA neurons chronic degeneration. Methods 30 healthy male SD rats were randomly assigned into normal saline（NS） control group and 50 μg LPS group.The rats were treated with intraventricularl injection of 20 μL NS or 50 μg LPS on right side.40 weeks later,OX-42 and OX-6 antibodies were used to detect whether the microglia were activated in the substantia nigra of rats.The morphology and numbers of DA neurons were observed by tyrosine hydroxylase（TH） immunohistochemical staining.The degenerated neurons were detected by using Fluoro-Jade B（FJB）. Results （1） At 40 weeks after injection,the OX-42 positive microglia in the substantia nigra of NS control group rats were quiescing with pale staining.There were numerous activated,darkly stained OX-42 positive microglia in the substantia nigra of 50 μg LPS group rats.OX-6 positive microglia were not found in both of the two groups.（2） There were numerous darkly stained TH-positive neurons in the substantia nigra of NS control group.The number of TH-positive neurons in the 50 μg LPS group rats（99.11±20.31） decreased by 47.7%（t=4.445,P0.01） compared with that of NS control group（189.52±12.12）.（3） There were no FJB positive neurons in the substantia nigra of both the two group rats. Conclusions Single intraventricular injection of 50 μg LPS may induce long-term chronic activation of microglia and chronic delayed functional injury to the DA neurons in the substantia nigra of rats.