College of Animal Science, Xinjiang Agricultural University, Urumqi 830052, China.
College of Animal Science and Technology, China Agricultural University, Beijing 100083, China.
Molecules. 2021 Aug 31;26(17):5275. doi: 10.3390/molecules26175275.
The purpose of this study is to investigate the potential effects of 5-hydroxytryptophan (5-HTP) duodenal perfusion on melatonin (MT) synthesis in the gastrointestinal (GI) tract of sheep. 5-hydroxytryptophan is a precursor in the melatonin synthetic pathway. The results showed that this method significantly increased melatonin production in the mucosa of all segments in GI tract including duodenum, jejunum, ileum, cecum and colon. The highest melatonin level was identified in the colon and this indicates that the microbiota located in the colon may also participate in the melatonin production. In addition, portion of the melatonin generated by the GI tract can pass the liver metabolism and enters the circulation via portal vein. The current study provides further evidence to support that GI tract is the major site for melatonin synthesis and the GI melatonin also contributes to the circulatory melatonin level since plasma melatonin concentrations in 5-HTP treated groups were significantly higher than those in the control group. In conclusion, the results show that 10-50 mg of 5-HTP flowing into the duodenum within 6 h effectively improve the production of melatonin in the GI tract and melatonin concentration in sheep blood circulation during the day.
本研究旨在探讨 5-羟色氨酸（5-HTP）十二指肠灌注对绵羊胃肠道（GI）褪黑素（MT）合成的潜在影响。5-羟色氨酸是褪黑素合成途径中的前体。结果表明，这种方法显著增加了 GI 道各段（包括十二指肠、空肠、回肠、盲肠和结肠）黏膜中的褪黑素生成。在结肠中鉴定出最高水平的褪黑素，这表明位于结肠中的微生物群也可能参与褪黑素的生成。此外，部分由 GI 道产生的褪黑素可以通过肝脏代谢，并通过门静脉进入循环。本研究进一步证明 GI 道是褪黑素合成的主要部位，并且 GI 褪黑素也有助于循环褪黑素水平，因为 5-HTP 处理组的血浆褪黑素浓度明显高于对照组。总之，结果表明，10-50mg 的 5-HTP 在 6 小时内流入十二指肠可有效提高 GI 道褪黑素的产生，并提高绵羊日间血液中的褪黑素浓度。
