First Department of Internal Medicine, University of Szeged, Korányi fasor 8-10, H-6720 Szeged, Hungary.
Gen Comp Endocrinol. 2011 May 15;172(1):181-3. doi: 10.1016/j.ygcen.2010.12.015. Epub 2010 Dec 25.
Grizzly bears (Ursus arctos horribilis) are inactive for up to 6 months during hibernation. They undergo profound seasonal changes in food intake, body mass, and energy expenditure. The circa-annual regulation of metabolism is poorly understood. In this study, we measured plasma ghrelin, leptin, obestatin, and neuropeptide-Y (NPY) levels, hormones known to be involved in the regulation of energy homeostasis, in ten grizzly bears. Blood samples were collected during the active summer period, early hibernation and late hibernation. Plasma levels of leptin, obestatin, and NPY did not change between the active and the hibernation periods. Plasma total ghrelin and desacyl-ghrelin concentrations significantly decreased during the inactive winter period compared to summer levels. The elevated ghrelin levels may help enhance body mass during pre-hibernation, while the low plasma ghrelin concentrations during hibernation season may contribute to the maintenance of hypophagia, low energy utilization and behavioral inactivity. Our results suggest that ghrelin plays a potential role in the regulation of metabolic changes and energy homeostasis during hibernation in grizzly bears.
灰熊（Ursus arctos horribilis）在冬眠期间长达 6 个月处于不活跃状态。它们在食物摄入、体重和能量消耗方面经历了明显的季节性变化。代谢的年度调节机制还不太清楚。在这项研究中，我们测量了 10 只灰熊的血浆胃饥饿素、瘦素、肥胖抑制素和神经肽 Y（NPY）水平，这些激素已知参与能量稳态的调节。在活跃的夏季、早期冬眠和晚期冬眠期间采集血液样本。在活跃期和冬眠期之间，瘦素、肥胖抑制素和 NPY 的血浆水平没有变化。与夏季水平相比，非酰化胃饥饿素和总胃饥饿素浓度在不活跃的冬季期间显著降低。升高的胃饥饿素水平可能有助于在冬眠前增加体重，而冬眠季节低水平的血浆胃饥饿素可能有助于维持少食、低能量利用和行为不活跃。我们的结果表明，胃饥饿素在灰熊冬眠期间的代谢变化和能量稳态调节中发挥了潜在作用。
