Nandar Wint, Milligan Justin M, Cline Mark A
Department of Neuroscience and Anatomy, Pennsylvania State University, P.O. Box 850, Hershey, PA 17033, USA.
Gen Comp Endocrinol. 2008 May 15;157(1):58-62. doi: 10.1016/j.ygcen.2008.03.012. Epub 2008 Mar 21.
We recently reported that the 25 amino acid peptide xenin caused reduced feed intake when centrally injected in chicks. The present study was designed to explore possible mechanisms of the xenin-induced anorexigenic response in chicks. In Experiments 1 and 2, chicks were implanted with cannulas and xenin injections were made directly into the ventromedialis hypothalami (VMH). Chicks responded with reduced feed intake and increased c-Fos immunoreactivity at the VMH. In Experiment 3 chicks that received co-intracerebroventricular (ICV) injection of naloxone and a dose of xenin (100 pmol), that alone does not affect feed intake, had reduced feed intake. In Experiment 4, chicks responded to ICV xenin with reduced feed- but increased exploratory-pecking. Thus, we conclude that xenin may mediate its effect directly at the VMH and that the endogenous opioid system may counter anorexigenic effects of low xenin doses in chicks. Xenin also caused increased exploration of a novel environment, an effect that may be competitive with feeding. Taken together, these results suggest that xenin regulation of chick appetite is the result of several central and behavioral mechanisms acting in synergism.
我们最近报道，25个氨基酸的肽外显肽在雏鸡中进行中枢注射时会导致采食量减少。本研究旨在探讨外显肽诱导雏鸡厌食反应的可能机制。在实验1和实验2中，给雏鸡植入套管，并将外显肽直接注射到下丘脑腹内侧核（VMH）。雏鸡的反应是采食量减少，VMH处的c-Fos免疫反应性增加。在实验3中，接受脑室内（ICV）注射纳洛酮和一剂外显肽（100 pmol）的雏鸡采食量减少，单独注射该剂量的外显肽不会影响采食量。在实验4中，雏鸡对ICV注射外显肽的反应是采食量减少，但探索性啄食增加。因此，我们得出结论，外显肽可能直接在VMH介导其作用，内源性阿片系统可能对抗雏鸡低剂量外显肽的厌食作用。外显肽还导致对新环境的探索增加，这种作用可能与进食相互竞争。综上所述，这些结果表明外显肽对雏鸡食欲调节是几种中枢和行为机制协同作用的结果。
