Hirvonen M D, Keesey R E
University of Wisconsin, Madison 53706, USA.
Physiol Behav. 1996 Sep;60(3):725-31. doi: 10.1016/0031-9384(96)00097-2.
Lesions of the lateral hypothalamus (LH) result in a body weight reduction characterized by declines in both lean and adipose tissues. The body fat of LH-lesioned rats can be restored to or above the levels of nonlesioned rats by overfeeding. However, the protein deficit cannot be so reversed, suggesting that the lesion-induced body protein reduction is chronic. To ascertain which specific tissues surrender protein following LH lesions, the present studies measured skeletal muscle and visceral organ weights at 2 weeks and 6 months postlesion. Daily protein losses during the first 2 weeks postlesion were also assessed to determine the temporal pattern of whole-body protein adjustments. The results at 6 months postlesion suggest that LH lesions lead to reductions in the maintained mass of all protein-based tissues. The largest absolute loss was from skeletal muscle, whereas liver sustained the greatest proportional loss. Assessment of daily postlesion protein balance indicate that the majority of body protein losses occurred during the initial 6 days postlesion. Skeletal muscle mass was characterized by large losses at 2 weeks, and proportionally smaller losses at 6 months. Reductions of visceral organ mass were marginal at 2 weeks, but substantial by 6 months postlesion. Thus, whereas all protein-based tissues are reduced by LH lesions, the protein content of specific tissues appears to be altered differentially. Major reductions in total body protein occur in the first 2 weeks of the LH syndrome, with an apparent redistribution of protein later. This redistribution results in the partial restoration of skeletal muscle at the expense of existing visceral organ protein or its subsequent accretion.
下丘脑外侧区（LH）损伤会导致体重减轻，其特征是瘦组织和脂肪组织均减少。通过过度喂养，LH损伤大鼠的体脂可恢复到非损伤大鼠的水平或更高。然而，蛋白质缺乏无法如此逆转，这表明损伤引起的机体蛋白质减少是慢性的。为了确定LH损伤后哪些特定组织会损失蛋白质，本研究测量了损伤后2周和6个月时骨骼肌和内脏器官的重量。还评估了损伤后前2周的每日蛋白质损失，以确定全身蛋白质调节的时间模式。损伤后6个月的结果表明，LH损伤导致所有基于蛋白质的组织的维持质量下降。绝对损失最大的是骨骼肌，而肝脏的比例损失最大。对损伤后每日蛋白质平衡的评估表明，机体蛋白质的大部分损失发生在损伤后的最初6天内。骨骼肌质量在2周时损失较大，在6个月时比例损失较小。内脏器官质量在2周时减少不明显，但在损伤后6个月时显著减少。因此，虽然LH损伤会使所有基于蛋白质的组织减少，但特定组织的蛋白质含量似乎有不同程度的改变。全身蛋白质的主要减少发生在LH综合征的前2周，随后蛋白质出现明显的重新分布。这种重新分布导致骨骼肌部分恢复，代价是现有内脏器官蛋白质或其随后的积累。
