Department of Oral Physiology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan.
J Mol Neurosci. 2011 Feb;43(2):217-24. doi: 10.1007/s12031-010-9475-1. Epub 2010 Nov 18.
Orexins are synthesized by lateral hypothalamic neurons and are suggested to be implicated in feeding behavior. Recent studies have shown that intracerebroventricular administration of orexin-A increases intake of sweet-tasting solution. Effects of suppressing the orexin system on consumption of sweet-tasting solution and sensory processing with sweet taste inputs, however, have yet to be examined. We examined the effects of orexin deficiency on sucrose solution intake, locomotor activity, and preference for sweet solution using male orexin knockout (OxKO) and littermate wild-type (WT) mice. In the dark and over 24-h periods, OxKO mice showed significantly less sucrose intake and lower locomotor activity than WT mice without alteration in food intake whereas preferences for 100 mM sucrose were not different between the genotypes. Moreover, sucrose intake of OxKO mice was significantly less than sucrose intake of a subgroup of WT mice with similar locomotor activity compared to that of OxKO mice. These results suggest that factors other than the lower energy expenditure due to lower locomotor activity are likely responsible for the decreased sucrose intake of OxKO mice. Orexin deficiency may lower the satiety threshold resulting in reduced sucrose intake, without altering food intake.
食欲素由下丘脑外侧神经元合成，被认为与摄食行为有关。最近的研究表明，侧脑室给予食欲素-A 可增加对甜味溶液的摄入。然而，抑制食欲素系统对甜味溶液摄入和甜味输入的感觉处理的影响尚未被研究。我们使用雄性食欲素敲除（OxKO）和同窝野生型（WT）小鼠，检查了食欲素缺乏对蔗糖溶液摄入、运动活动和对甜味溶液偏好的影响。在黑暗中和 24 小时期间，OxKO 小鼠的蔗糖摄入量和运动活动显著低于 WT 小鼠，而食物摄入量没有改变，而两种基因型对 100mM 蔗糖的偏好没有差异。此外，与 OxKO 小鼠相比，OxKO 小鼠的蔗糖摄入量明显低于运动活性相似的 WT 小鼠亚组的蔗糖摄入量。这些结果表明，由于运动活动降低导致的较低能量消耗以外的因素可能导致 OxKO 小鼠蔗糖摄入量减少。食欲素缺乏可能降低饱腹感阈值，导致蔗糖摄入量减少，而不改变食物摄入量。
