a Neuroscience Research Laboratory, Dr. Panjwani Center for Molecular Medicine and Drug Research , University of Karachi , Karachi 75270 , Pakistan.
b Department of Physiology , Wah Medical College , Wah Cantt , Pakistan.
Nutr Neurosci. 2019 Jun;22(6):409-417. doi: 10.1080/1028415X.2017.1395551. Epub 2017 Nov 3.
Stress in known to alter hormonal systems. Pharmacological doses of tryptophan, the essential amino acid precursor of serotonin, increase circulating leptin and decrease ghrelin in normal healthy adults. Because systemically injected leptin inhibits stress-induced behavioral deficits and systemically injected serotonin modulates leptin release from the adipocytes, we used tryptophan as a pharmacological tool to modulate hormonal and behavioral responses in unstressed and stressed rats.
Leptin, ghrelin, serotonin, tryptophan, and behavior were studied in unstressed and stressed rats following oral administration of 0, 100, 200, and 300 mg/kg of tryptophan.
Following oral administration of tryptophan at a dose of 300 mg/kg, circulating levels of serotonin and leptin increased and those of ghrelin decreased in unstressed animals. No effect occurred on 24-hours cumulative food intake and elevated plus maze performance. Exposure to 2 hours immobilization stress decreased 24 hours cumulative food intake and impaired performance in elevated plus maze monitored next day. Serum serotonin decreased, leptin increased, and no effect occurred on ghrelin. Stress effects on serotonin, leptin, food intake, and elevated plus maze performance did not occur in tryptophan-pretreated animals. Tryptophan-induced decreases of ghrelin also did not occur in stressed animals.
The findings show an important role of serum serotonin, leptin, and ghrelin in responses to stress and suggest that the essential amino acid tryptophan can improve therapeutics in stress-induced hormonal and behavioral disorders.
压力会改变激素系统。色氨酸是 5-羟色胺的必需氨基酸前体，药理学剂量的色氨酸可增加正常健康成年人的循环瘦素并降低胃饥饿素。由于系统注射的瘦素可抑制应激引起的行为缺陷，而系统注射的 5-羟色胺可调节脂肪细胞中瘦素的释放，因此我们使用色氨酸作为药理学工具来调节未应激和应激大鼠的激素和行为反应。
在未应激和应激大鼠中，经口给予 0、100、200 和 300mg/kg 色氨酸后，研究了瘦素、胃饥饿素、5-羟色胺、色氨酸和行为。
经口给予 300mg/kg 色氨酸后，未应激动物的循环 5-羟色胺和瘦素水平升高，胃饥饿素水平降低。24 小时累积食物摄入量和高架十字迷宫表现没有变化。暴露于 2 小时固定应激会减少 24 小时累积食物摄入量，并损害次日监测的高架十字迷宫表现。血清 5-羟色胺降低，瘦素升高，胃饥饿素无变化。应激对血清 5-羟色胺、瘦素、食物摄入量和高架十字迷宫表现的影响不会发生在色氨酸预处理的动物中。应激动物也不会发生色氨酸诱导的胃饥饿素降低。
这些发现表明血清 5-羟色胺、瘦素和胃饥饿素在应激反应中起重要作用，并表明必需氨基酸色氨酸可以改善应激引起的激素和行为障碍的治疗方法。
