新生大鼠脑低氧缺血早期对纹状体胆碱能系统的影响

EFFECTS OF EARLY CEREBRAL HYPOXIAHSCHEMIA ON STRIATAL CHOLINERGIC SYSTEM IN NEW-BORN RATS

采用7日龄大鼠右侧颈总动脉结扎合并高温、低氧环境制作新生动物脑低氧缺血模型,观察了脑低氧缺血对新生动物纹状体胆碱能系统的影响。乙酰胆碱(ACh)放射免疫测定结果表明,低氧缺血损伤后24h,两侧纹状体ACh含量均比正常对照组明显下降。乙酰胆碱酯酶(AChE)组织化学图象定量提示,脑低氧缺血后24h,纹状体内拟胆碱能神经元数量未见减少,而胞体内AChE染色强度略有下降。胆碱能递质和该标志酶在新生鼠脑低氧缺血早期的一致改变,证明发育中纹状体胆碱能系统对低氧缺血敏感。鉴于动物不结扎动脉仅作低氧处理者双侧纹状体ACh含量出现与低氧缺血组相同的改变,故提示缺氧可能是造成胆碱能系统早期损伤的直接原因。

The animal model of postnatal cerebral hypoxia-ischemia was prepared in 7 days old rats by permanent ligation of right common carotid artery combined with a temporary systemic hypoxia at 37℃. The early effects of hypoxia-ischemia on the striatal cholinergic system were investigated 24 h after lesion by ACh RIA-determination and AChE-histochemical image analysis. The striatal ACh content and average optical density of the AChE-positive cell bodies declined by 28 % and 12% respectively in the hypoxic-ischemic group as compared with the normal control group (p<0.01, p<0.05). There was no difference in the values between the ligated and non-ligated sides in the hypoxic-ischemic group. The striatal ACh content in the animals of the hypoxic group, which was prepared by temporary exposure to hypoxia at 37℃ with the carotid arteries intact, was also found to be reduced to the same extent as in the hypoxic-ischemic group. The density of AChE-positive cell profiles in the caudate-putamen remained unchanged on both sides in the hypoxic-ischemic group. The results indicate that hypoxia-ischemia, at its early phase, brings about cell damage rather than cell death and, as a result, leads to the weakening of the neuron markers, ACh and AChE in this case of the striatal cholinergic system of the young rat. It is suggested that developing cholinergic system is susceptible to hypoxia-ischemia, probably with anoxia as the primary pathogeny.