Yu J H, Smith C B
Pharmacology. 1977;15(3):242-53. doi: 10.1159/000136695.
Uptake and metabolism of 3H-5-dydroxytryptamine (3H-5-HT) in slices of hypothalamus, brain stem caudate nucleus and parietal cortex were examined in vitro. The results indicate that 3H-5-HT taken up by neurons is firmly retained and that there are regional differences in the uptake and retention of 3H-5-HT. For example, the caudate had a significantly greater maximum rate of uptake and binding (Vmax) than the other brain areas tested, particularly the cortex. In contrast the caudate appeared to have the lowest apparent for 3H-5-HT uptake (Km). Uptake and retention of 3H-5-HT by four brain areas were markedly inhibited by cocaine and desmethylimipramine (DMI) in vitro. The inhibitory effect of both drugs was noncompetitive in nature, with exception of thct that cocaine and DMI failed to reduce the formation of 3H-5-hydroxy-indoleacetic acid despite ther potent blocking action of 3H-5-HT uptake suggests that a significant amount of 3H-5-HT is oxidatively deaminated at extraneouronal sites. This extraneuronal metabolism of 5-hydroxytryptamine may play an play an important role in regulating the action of this neurotransmitter.
在体外研究了下丘脑、脑干尾状核和顶叶皮质切片对3H - 5 - 羟色胺（3H - 5 - HT）的摄取和代谢。结果表明，神经元摄取的3H - 5 - HT被牢固保留，并且3H - 5 - HT的摄取和保留存在区域差异。例如，尾状核的最大摄取和结合速率（Vmax）明显高于其他测试脑区，尤其是皮质。相比之下，尾状核对3H - 5 - HT摄取的表观亲和力（Km）似乎最低。体外实验中，可卡因和去甲丙咪嗪（DMI）显著抑制了四个脑区对3H - 5 - HT的摄取和保留。两种药物的抑制作用本质上是非竞争性的，不过可卡因和DMI尽管对3H - 5 - HT摄取有强大的阻断作用，但未能减少3H - 5 - 羟吲哚乙酸的形成，这表明大量的3H - 5 - HT在细胞外部位发生了氧化脱氨。5 - 羟色胺的这种细胞外代谢可能在调节这种神经递质的作用中发挥重要作用。
