甲状腺激素对大鼠脑皮质发育期突触体素表达的影响

目的探讨甲状腺激素（TH）对发育关键期大鼠大脑皮质突触体素（syn）表达的作用和影响。方法选用甲巯咪唑（MM）复制甲状腺机能减退大鼠模型,实验分成正常对照组（n=42）和甲减组两组（n=36）,收集出生后第0,4,7,14,21,30,120天的正常、甲减组仔鼠脑组织。采用原位杂交组织化学法检测发育关键期仔鼠大脑皮质突触体素的表达变化情况。结果正常对照组syn mRNA在生后不同发育阶段的表达变化明显且具有层状分布的特点。生后第0天表达很低,在第4天表达最高。以后表达逐渐下降,至第30天表达水平基本接近于成年鼠水平（P120d）。甲减组synmRNA表达在各时点均明显低于正常对照组（P〈0.001）。甲减组syn mRNA表达高峰延迟3d,在出生后第7天达到高峰。结论在脑发育关键期,甲状腺激素水平的异常改变了大脑皮质突触体素的表达,进一步影响了其突触的发生及相关神经回路的建立,出现神经元的旷置或错误神经通路,阻碍了脑发育与其功能的成熟。

Effect of thyroid hormones on expression of synaptophysin in the developing rat cortex

Objective To investigate the effects of thyroid hormone(TH)on the synaptophysin(syn)expression in the developing rat cortex.Methods The hypothyroidism model of rats were established by pre-treating with thiamazole.The rats were divided into normal group(n=42)and hypothyroidism group(n=36).The rats brain were collected at the postnatal days 0,4,7,14,21,30 and 120.The expression of syn mRNA in neocortex was detected by in situ hybridization method.Result In normal control group,syn mRNA expression had significant difference with layer distribution at different postnatal times.The expression was very low at postnatal day 0,peaked at postnatal day 4,and then decreased gradually.At postnatal day 30,the expression of the syn mRNA was near to that of adult rat(P120 d).In hypothyroidism group,syn mRNA expression were significantly lower than those in normal control group(P<0.001),and peaked at postnatal day 7.Conclusion In the critical period of brain development,abnormality of thyroid hormone leads to the change of syn mRNA expression in the rat cortex,further affects synapses occurrence and related nerve circuit establishment,causes the peerless of the neuron place or mistake nerve pathway,therefore,the brain development and function maturation are obstructed.