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The Structure and Changes of International Feed Trade : A Network Analysis Approach
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Practical environmental education report in accordance with the elementary school national curriculum standards : A case study on using environmental education as teaching material for the special subject “morality”
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書籍紹介 : 『大蛇全書』田原義太慶編著 柴田弘紀・友永達也共著 : 2022年3月 グラフィック社 発行 384頁 定価 4,950円 (本体 4,500円+税)
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Does motilin regulate gastrointestinal motility in the chicken?
Get PDFBulletinMotilin is a peptide hormone released from M cells in the duodenal mucosa and it stimulates gastrointestinal (GI) motility. In mammals (dogs, humans, opossums, monkeys and suncus), plasma motilin level fluctuates periodically and its peak is consistent with the appearance of phase III of gastric migrating motor complex (MMC), and motilin induces MMC-like actions. Therefore, motilin is considered to be an endogenous mediator of the phase III of gastric MMC. However, motilin does not induce MMC-like actions in rabbits, pigs and sheep, suggesting that there are marked species differences in the physiological roles of motilin even in mammals. Chickens also have motilin and its receptor, but the amino acid sequence of chicken motilin in the N-terminal region (1-10), which is important for biological activity, is notably different from that of mammals, and homology of the receptor is about 60% of the human motilin receptor. Due to the difference in the receptor structures, differences in responsiveness of motilin receptor agonists and antagonists are observed in the chicken GI tract. GI tract-stimulating action of motilin was observed in the proventriculus and small intestine, and the small intestine showed high efficacy and high affinity to motilin. In vivo measurements of GI motility in the chicken showed the presence of MMC-like motility that migrates from the jejunum to the ileum both in the fasting and postprandial periods and the presence of rhythmic oscillating complex (ROC), which was contractions migrating up and down between the proximal duodenum and distal ileum in the fasting periods. Motilin did not affect MMC in the jejunum but was found to induce ROC, and plasma motilin levels were high during the appearance of ROCs. These observations suggest that motilin is a regulator of ROC not MMC in the chicken. ROC might be involved in the growth of chickens by mixing intestinal nutrients well and increasing the absorption of nutrients. In fact, it has been shown that growth speed varies among motilin receptor genotypes and that chickens with a high expression level of motilin receptor mRNA in the proventriculus grow faster than do those with a low expression level. It is speculated that motilin/motilin receptor in chickens stimulates GI motility such as ROC and then the increase in absorption of nutrients affects the growth speed. The focus on motilin and its receptors in chickens could lead to selection and breeding of a high speed-growth variety. Further studies on functions of motilin and its receptor in avian species such as chickens are needed in the future.departmental bulletin pape
