Gietzen D W, Rogers Q R, Leung P M, Semon B, Piechota T
Department of Physiological Sciences, School of Veterinary Medicine, University of California, Davis 95616.
Am J Physiol. 1987 Nov;253(5 Pt 2):R763-71. doi: 10.1152/ajpregu.1987.253.5.R763.
The role of serotonin in the anorexic response of rats to an amino acid-imbalanced diet was investigated. After chronic depletion of serotonin with parachlorophenylalanine (PCPA, 300 mg/kg) or 5,7-dihydroxytryptamine (DHT, 200 micrograms/rat, intracisternally), initial intake of a mild isoleucine-imbalanced diet was reduced by 60% vs. a 17% reduction after saline injection. After acute treatment with the agonist, quipazine (quip, 5 mg/kg ip) or the precursor, tryptophan (TRP, 1% added to the diet), imbalanced diet intake was also exacerbated. PCPA and DHT may have caused receptor supersensitivity, such that the food intake depression after serotonin depletion was similar to that seen with the quip and TRP treatments. Injection of the autoreceptor agonist, 8-hydroxy-2(di-n-propylamino)tetralin (8-OH-DPAT, 500 micrograms/kg sc), to reduce transmission in the serotonergic systems resulted in an attenuation of the usual food intake depression of the amino acid-imbalanced diet (only a 7%, nonsignificant reduction). Also measurements made in the absence of pharmacological treatment showed that the ratio 5-hydroxyindole acetic acid-to-serotonin, a putative index of serotonin turnover, was increased 155% in the raphe nuclei and 140% in the hippocampus 3.5 h after ingestion of the mild isoleucine-imbalanced diet. Therefore increased serotonergic activity in some brain areas may be associated with the initial depression of food intake in rats fed an imbalanced amino acid diet.
研究了血清素在大鼠对氨基酸不平衡饮食的厌食反应中的作用。在用对氯苯丙氨酸（PCPA，300mg/kg）或5,7 - 二羟基色胺（DHT，200微克/大鼠，脑池内注射）长期耗尽血清素后，轻度异亮氨酸不平衡饮食的初始摄入量比注射生理盐水后减少了60%，而注射生理盐水后减少了17%。在用激动剂喹哌嗪（quip，5mg/kg腹腔注射）或前体色氨酸（TRP，饮食中添加1%）进行急性治疗后，不平衡饮食的摄入量也增加了。PCPA和DHT可能导致了受体超敏，使得血清素耗竭后的食物摄入量降低类似于喹哌和TRP治疗后的情况。注射自身受体激动剂8 - 羟基 - 2（二正丙基氨基）四氢萘（8 - OH - DPAT，500微克/千克皮下注射）以减少血清素能系统中的传递，导致氨基酸不平衡饮食通常的食物摄入量降低有所减轻（仅降低7%，无统计学意义）。此外，在未进行药物治疗的情况下进行的测量表明，摄入轻度异亮氨酸不平衡饮食3.5小时后，5 - 羟吲哚乙酸与血清素的比率（血清素周转的一个假定指标）在中缝核中增加了155%，在海马体中增加了140%。因此，某些脑区血清素能活性增加可能与喂食不平衡氨基酸饮食的大鼠食物摄入量的初始降低有关。
