不同甲状腺功能状态对成年大鼠中枢5—HT1A受体密度的影响

用三碘甲状腺原氨酸(T_3)和丙基硫氧嘧啶(PTU)灌胃分别制成大鼠的甲状腺机能亢进症(简称甲亢)和甲状腺机能低下症(简称甲低)模型。灌药后甲亢组心率、氧耗量、肛温以及血浆T_3浓度较对照组显著增高;在甲低组则均降低。氚标8-羟基-2-(二正丙氨基)-四氢化萘([~3H]8-OH-DPAT)的受体结合实验显示甲亢组海马的5-HT_(1A)受体结合数较对照组显著增加,皮层减低,下丘脑、脑干和纹状体无显著变化。Scatchard分析示甲文组[~3H]8-OH-DPAT在海马中的最大结合容量(B_(max))增加,皮层减低,K_D无变化。甲低组在上述脑区均未见显著变化。上述5-HT_(1A)受体的变化是否与甲亢并发精神神经障碍的机制有关,尚待进一步研究。

EFFECTS OF DIFFERENT THYROID STATES ON 5-HT_(1A) RECEPTOR IN ADULT RAT BRAIN

The effects of dysthyroidism on central 5-HT_(1A) receptor subtype in adult Wis-tar rats were investigated. Hyperthyroidism and hypothyrodism were respec-tively produced with the administration of T_3 and propylthiouracil (PTU) via ga-vage for 2 weeks. Heart rate, oxygen consumption, anal temperature and plasmaT_3 concentration were increased in hyperthyroid rats and decreased in hypothy-roid rats significantly. Radioligand binding assay showed that the specific bindingof [~3H] 8-hydroxy-2 - (di-n-propylamino) tetralin ([~3H] 8-OH-DPAT) at 0.6 nmol/Lconcentration was highest in hippocampus, next in cerebral cortex, and lowestin hypothalamus, brain stem and corpus striatum in euthyroid rats. Hyperthy-roidism increased the binding significantly in hippocampus but decreased in cor-tex. No change was found in the other brain regions. Scatchard analyses re-vealed that the B_(max) was increased in hippocampus and decreased in cortex, whereasthe K_D was not consistently affected in hyperthyroid rats in comparison with thatin euthyroid rats. However, there were no significant changes mentioned abovein all these brain regions of hypothyroid rats. Our results indicate that there seems to exist an imbalance of the serotoner-gic activity mediated via 5-HT_(1A) receptor between hippocampus and cerebral cor-tex in hyperthyroids. This might be one of the mechanisms leading to psycho-neural disorders in hyperthyroidism.