Trouvin J H, Maubrey M C, Raynal H, Jacquot C
UA CNRS 594, Faculté de Pharmacie, Châtenay-Malabry, France.
Fundam Clin Pharmacol. 1991;5(6):497-502. doi: 10.1111/j.1472-8206.1991.tb00736.x.
The time course of 5-hydroxytryptophan (5-HTP), serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) concentrations in four rat brain areas (hypothalamus, hippocampus, striatum and olfactory bulbs) were investigated after treatment with L-dopa (125 mg/kg, ip) + benserazide (50 mg/kg, ip). 5-HTP levels increased as early as 0.5 h, showed maximum accumulation at 1.5 h and returned to control levels within 4 h, while 5-HT was markedly decreased in all four structures, with a maximum effect at 1.5 h (approximately -70%) in the four areas. The decrease in 5-HT was not accompanied by changes in 5-HIAA levels. In agreement with previous studies, these data demonstrate that L-dopa loading interferes with serotonin metabolism in the rat brain. However, in addition to the releasing action of newly-synthesized dopamine, the accumulation of 5-HTP and the parallel decrease in 5-HT indicate a reduction in 5-HT synthesis. This inhibition could be explained by a competitive effect of L-dopa for aromatic aminoacid decarboxylase activity.
在用左旋多巴（125毫克/千克，腹腔注射）+苄丝肼（50毫克/千克，腹腔注射）治疗后，研究了四种大鼠脑区（下丘脑、海马体、纹状体和嗅球）中5-羟色氨酸（5-HTP）、血清素（5-HT）和5-羟吲哚乙酸（5-HIAA）浓度的时间进程。5-HTP水平早在0.5小时就开始升高，在1.5小时达到最大积累，并在4小时内恢复到对照水平，而在所有四个结构中5-HT均显著降低，在四个区域中1.5小时时达到最大效应（约-70%）。5-HT的降低并未伴随5-HIAA水平的变化。与先前的研究一致，这些数据表明左旋多巴负荷会干扰大鼠脑中血清素的代谢。然而，除了新合成多巴胺的释放作用外，5-HTP的积累和5-HT的平行降低表明5-HT合成减少。这种抑制作用可以用左旋多巴对芳香族氨基酸脱羧酶活性的竞争效应来解释。
