Saneyasu Takaoki, Fukuzo Satoshi, Kitashiro Ayana, Nagata Kanami, Honda Kazuhisa, Kamisoyama Hiroshi
Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan.
Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan.
Physiol Behav. 2019 Oct 15;210:112644. doi: 10.1016/j.physbeh.2019.112644. Epub 2019 Aug 6.
Several studies in rodents and layer chickens have demonstrated that insulin upregulates hypothalamic AKT-mediated signaling and expression of proopiomelanocortin (POMC, the precursor of alpha-melanocyte stimulating hormone, an anorexigenic peptide) and suppresses appetite in these animals. However, a previous study has also reported that insulin fails to suppress food intake in broiler chicks. In the present study, no significant differences were observed in hypothalamic AKT and forkhead box O1 (FOXO1) phosphorylation levels between broiler and layer chicks. The phosphorylation rate of AKT, but not that of FOXO1, increased in the hypothalami of broilers refed for 1 h after a 24-h fast, with a corresponding increase in plasma insulin concentration. Intracerebroventricular (ICV) administration of 50 pmol insulin, which could decrease food intake in broiler chicks, significantly increased the AKT phosphorylation rate, whereas no significant change was observed in FOXO1 phosphorylation or POMC expression after ICV insulin administration. These findings suggest that hypothalamic AKT responds to insulin in broiler chicks, but FOXO1-mediated regulation of POMC expression is not induced by insulin, which may be one of the causes of excessive food intake in broiler chickens.
多项针对啮齿动物和蛋鸡的研究表明，胰岛素可上调下丘脑AKT介导的信号传导以及阿黑皮素原（POMC，α-黑素细胞刺激素的前体，一种厌食肽）的表达，并抑制这些动物的食欲。然而，此前有一项研究也报道称胰岛素无法抑制肉鸡的采食量。在本研究中，未观察到肉鸡和蛋鸡之间下丘脑AKT和叉头框O1（FOXO1）磷酸化水平存在显著差异。禁食24小时后再喂食1小时的肉鸡下丘脑内，AKT的磷酸化率升高，而FOXO1的磷酸化率未升高，同时血浆胰岛素浓度相应增加。脑室内（ICV）注射50 pmol胰岛素可降低肉鸡的采食量，显著提高AKT磷酸化率，而ICV注射胰岛素后FOXO1磷酸化或POMC表达未观察到显著变化。这些发现表明，肉鸡下丘脑的AKT对胰岛素有反应，但胰岛素不会诱导FOXO1介导的POMC表达调节，这可能是肉鸡采食量过多的原因之一。
