Näslund E, Ehrström M, Ma J, Hellström P M, Kirchgessner A L
The Division of Surgery, Danderyd Hospital Karolinska Institutet, SE-182 88 Stockholm, Sweden.
Am J Physiol Gastrointest Liver Physiol. 2002 Mar;282(3):G470-9. doi: 10.1152/ajpgi.00219.2001.
The orexins [orexin A (OXA) and orexin B (OXB)] are novel neuropeptides that increase food intake in rodents. The aim of this study was to determine the distribution of orexin and orexin receptors (OX1R and OX2R) in the rat duodenum and examine the effects of intravenous orexin on fasting gut motility. OXA-like immunoreactivity was found in varicose nerve fibers in myenteric and submucosal ganglia, the circular muscle, the mucosa, submucosal and myenteric neurons, and numerous endocrine cells of the mucosa. OXA neurons displayed choline acetyltransferase immunoreactivity, and a subset contained vasoactive intestinal peptide. OXA-containing endocrine cells were identified as enterochromaffin (EC) cells based on the presence of 5-hydroxytryptamine immunoreactivity. OX1R was expressed by neural elements of the gut, and EC cells expressed OX2R. OXA at 100 and 500 pmol x kg(-1) x min(-1) significantly increased the myoelectric motor complex (MMC) cycle length compared with saline. Similarly, OXB increased the MMC cycle length at 100 pmol x kg(-1) x min(-1), but there was no further effect at 500 pmol x kg(-1) x min(-1). We postulate that orexins may affect the MMC through actions on enteric neurotransmission after being released from EC cells and/or enteric neurons.
食欲肽[食欲肽A（OXA）和食欲肽B（OXB）]是一类新型神经肽，可增加啮齿动物的食物摄入量。本研究旨在确定食欲肽及食欲肽受体（OX1R和OX2R）在大鼠十二指肠中的分布，并研究静脉注射食欲肽对禁食时肠道运动的影响。在肌间神经节和黏膜下神经节的曲张神经纤维、环行肌、黏膜、黏膜下和肌间神经元以及黏膜的大量内分泌细胞中发现了OXA样免疫反应性。OXA神经元表现出胆碱乙酰转移酶免疫反应性，其中一部分含有血管活性肠肽。基于5-羟色胺免疫反应性的存在，含OXA的内分泌细胞被鉴定为肠嗜铬（EC）细胞。肠道的神经成分表达OX1R，而EC细胞表达OX2R。与生理盐水相比，100和500 pmol·kg-1·min-1的OXA显著增加了肌电运动复合波（MMC）的周期长度。同样，100 pmol·kg-1·min-1的OXB增加了MMC的周期长度，但在500 pmol·kg-1·min-1时没有进一步的作用。我们推测，食欲肽从EC细胞和/或肠道神经元释放后，可能通过作用于肠道神经传递来影响MMC。
