甲状腺素与甲巯咪唑对大鼠视前区与下丘脑前部温度敏感神经元的影响

本文观察了皮下注射甲状腺素和胃饲甲巯咪唑对大鼠视前区-下丘脑前部(PO/AH)温度敏感神经元的影响。PO/AH 存在温度敏感神经元(TSN)和温度不敏感神经元(TIN),在 TSN 中又可分为热敏神经元(WSN)和冷敏神经元(CSN)。在正常大鼠,TSN∶TIN=1.43∶1;WSN∶CSN=1.86∶1。以上比例可被甲状腺素和甲巯咪唑所改变:前者使之分别下降为1∶2.36和1.20∶1;后者使 TSN∶TIN 下降为1∶1.29,WSN∶CSN 上升为2.40∶1。各组神经元构成比有显著性差异,(X_2=9.64,P<0.05)。正常大鼠中所记录到的高频神经元(>15H_z)占32%(11/34),甲状腺素组仅有8%(3/37),甲巯咪唑组为9%(3/32)。实验中还发现甲状腺素组和甲巯咪唑组中 TSN 对热刺激的耐受性显著低于正常组。以上结果提示:甲状腺素或甲巯咪唑所致体温上升或下降可能与 PO/AH 神经元兴奋性及比例等改变有关;甲状腺素合成、释放和代谢的紊乱可以在下丘脑水平干扰体温调节过程;但这一作用的具体途径有待于进一步研究。

EFFECTS OF THYROXINE AND METHIMAZOLUM ON THERMOSENSITIVE NEURONS IN PREOPTIC/ANTERIOR HYPOTHALAMIC AREA IN RATS

The effects of thyroxine(subcutaneous injection)and methimazolum(intuba-tion feeding)on thermosensitive neurons(TSN)in the preoptic/anterior hypothala-mic(PO/AH)area in rats were observed.The ratio of warm-sensitive neurons(WSN)to cold-sensitive neurons(CSN)was 1.86:I and thermo-insensitive neurons(TIN)to thermosensitive neurons(TSN)1:1.43 in the control group.The ratioof WSN to CSN decreased to 1.20:1 and the ratio of TIN to 1:2.36 in the thyro-xine group,while the former increased to 2.40:1 and the latter decressed to 1:1.29in the methimazolum group.There was significant difference among three groups,(X~2=9.64,P<0.05).Thirty-two percent of neurons(11/34)showed higher firingrates(>15Hz)in the control group,only 8%(3/37)in the thyroxine group and9%(3/32)in the methimazolum group.In addition,the tolerance of TSN to warm-ing stimulation was obviously lower in both pathological groups,as comparedwith the control group.The rcsults suggest that a rise or fall of body temperaturein rats with subcutaneous injecting thyroxine and intubation feeding methima-zolum may be related to the changes of proportion and excitability of PO/AHneurons,and that the disturbance of thyroxine synthesis,release and metabolismmay interfere temperature regulation at the level of hypothalamus.