Laboratory of Veterinary Physiology, Division of Biosciences, Department of Veterinary Medicine, School of Veterinary Medicine, Rakuno Gakuen University, Japan.
Laboratory of Veterinary Physiology, Division of Biosciences, Department of Veterinary Medicine, School of Veterinary Medicine, Rakuno Gakuen University, Japan.
Neuropeptides. 2022 Dec;96:102293. doi: 10.1016/j.npep.2022.102293. Epub 2022 Sep 20.
The present study aimed to determine the effect and mode of action of the intravenous injection of xenin-25 on cyclic contractions of the rumen in healthy conscious sheep and mode of its action. Clinically healthy male sheep were equipped with a rumen cannula by surgery under anesthesia, and ruminal contractions were recorded with manometry in conscious animals after the recovery period. Intravenous xenin-25 injection induced a cluster of premature ruminal phasic contractions in a dose-dependent manner between 0.03 and 1 nmol/kg, and the change at the highest dose was statistically significant. In contrast, intravenous neurotensin injection inhibited the amplitude of cyclic rumen contractions. The xenin-25 effect was not significantly altered by prior injection of the neurotensin receptor subtype-1 antagonist SR 48692 at 30 and 100 nmol/kg. After euthanasia the ruminal muscles were excised for in vitro experiments. A single xenin-25 application (0.3-10 μM) to the longitudinal and circular muscle strips of the rumen did not induce any change in tension or electric field stimulation-induced phasic contractions of the muscle strips. These results demonstrated that circulating xenin-25 stimulates rumen contractions by acting on sites except the intramural intrinsic nerve plexus or smooth muscles of the rumen, implying that xenin-25 acts on the gastric center and/or cholinergic efferent nerve innervated to the ovine rumen.
本研究旨在确定静脉注射 Xenin-25 对健康绵羊意识中瘤胃周期性收缩的作用和作用方式及其作用模式。通过麻醉下的手术，将临床健康的雄性绵羊配备瘤胃插管，并在恢复期后对清醒动物进行测压以记录瘤胃收缩。静脉注射 Xenin-25 以 0.03 至 1 nmol/kg 的剂量依赖性方式诱导一系列过早的瘤胃相位收缩，最高剂量的变化具有统计学意义。相比之下，静脉注射神经降压素抑制了周期性瘤胃收缩的幅度。先前注射神经降压素受体亚型-1 拮抗剂 SR 48692（30 和 100 nmol/kg）并未显著改变 Xenin-25 的作用。安乐死后，取出瘤胃肌肉进行体外实验。单次 Xenin-25 应用（0.3-10 μM）于瘤胃的纵肌和环肌条上，不会引起张力或电场刺激引起的肌肉条相位收缩的任何变化。这些结果表明，循环中的 Xenin-25 通过作用于除了瘤胃壁内固有神经丛或平滑肌之外的部位来刺激瘤胃收缩，这意味着 Xenin-25 作用于胃中枢和/或支配绵羊瘤胃的胆碱能传出神经。
