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目的 探讨甲状腺功能低下 (甲低 )大鼠中枢 5 -羟色胺 (5 - HT)系统的代谢变化与机制 ,以及 5 - HT对促甲状腺激素 (TSH)分泌的调节作用。方法 用 0 .5 % Na Cl O4诱导实验大鼠甲低功 ,采用荧光分析方法测定大鼠脑组织 5 - HT、5 - HIAA含量及 MAO活性 ,放免法测定血清 T3、T4及 TSH含量。结果 甲低组大鼠血清 T3、T4含量明显下降 ,而血清 TSH含量及脑组织中 5 - HIAA、5 - HIAA/5 - HT比值、MAO活性显著升高 ,且 5 - HIAA、5 - HIAA/5 - HT比值与 MAO活性的变化呈正相关 ,r值分别为 0 .5 9、0 .5 7,P <0 .0 1。5 - HIAA、5 - HIAA/5 - HT比值与 TSH的变化也呈正相关 ,r值分别为 0 .6 9、0 .6 4,P <0 .0 1。而 5 - HIAA与血清 T3、T4则呈负相关 ,r值分别为 - 0 .74、- 0 .6 8,P <0 .0 1。结论 甲低大鼠中枢 5 - HT代谢活跃 ,其机制主要是通过调节 MAO活性而实现 ;中枢 5 - HT对 TSH的分泌有促进作用 ,在甲状腺激素对 TSH的负反馈调节中 ,5 - HT可能是中间环节之一。
Objective To investigate the metabolic changes and mechanisms of 5 - hydroxytryptamine (5 - HT) system in the rat with hypothyroidism and the regulatory effect of 5 - HT on the secretion of thyroid stimulating hormone (TSH). Methods The experimental hypothyroidism was induced by 0.5% NaCl O4 in rats. The content of 5 - HT and 5 - HIAA and the activity of MAO in rat brain were measured by fluorescence analysis. The contents of T3, T4 and TSH in serum were determined by radioimmunoassay. Results Serum levels of T3 and T4 in the hypothyroidism group decreased significantly, while serum TSH level and the ratio of 5 - HIAA, 5 - HIAA / 5 - HT and MAO activity were significantly increased in the hypothyroidism group. The levels of 5 - HIAA and 5 - HIAA / There was a positive correlation between the ratio of 5 - HT and the activity of MAO, the values of r were 0.59,0.57, P <0. 1.5 - HIAA, 5 - HIAA / 5 - HT and TSH, respectively Was positively correlated, r values were 0. 6 9,0. 64, P <0. However, 5 - HIAA was negatively correlated with serum T3 and T4, with r values of -0.74 and -0.68 respectively (P <0.01). Conclusion Central 5 - HT is metabolically active in hypothyroid rats, and its mechanism is mainly through the regulation of MAO activity. Central 5 - HT can promote TSH secretion. In the negative feedback regulation of thyroid hormone on TSH, 5 - HT may be Is one of the links.