Sorensen Annette, Adam Clare L, Findlay Pat A, Marie Michel, Thomas Louise, Travers Maureen T, Vernon Richard G
Hannah Research Institute, Ayr KA6 5HL, United Kingdom.
Am J Physiol Regul Integr Comp Physiol. 2002 Apr;282(4):R1227-35. doi: 10.1152/ajpregu.00595.2001.
Peripheral and hypothalamic mechanisms underlying the hyperphagia of lactation have been investigated in sheep. Sheep were fed ad libitum and killed at 6 and 18 days of lactation; ad libitum-fed nonlactating sheep were killed as controls. Despite increased food intake, lactating ewes were in negative energy balance. Lactation decreased plasma leptin and adipose tissue leptin mRNA concentrations. OB-Rb gene expression, determined by in situ hybridization, was increased in the hypothalamic arcuate nucleus (ARC) and ventromedial hypothalamic nucleus (VMH) at both stages of lactation. Neuropeptide Y (NPY) was increased by lactation in both the ARC and dorsomedial hypothalamus (DMH), although increased gene expression in the DMH was only apparent at day 18 of lactation. Gene expression was decreased for cocaine- and amphetamine-regulated transcript (CART) in the ARC and VMH and for proopiomelanocortin in ARC during lactation. Agouti-related peptide gene expression was increased in the ARC, and melanocortin receptor expression was unchanged in both the ARC and VMH with lactation. Thus the hypoleptinemia of lactation may activate NPY orexigenic pathways and attenuate anorexigenic melanocortin and CART pathways in the hypothalamus to promote the hyperphagia of lactation.
研究人员在绵羊身上探究了泌乳期食欲亢进背后的外周和下丘脑机制。绵羊自由采食，并在泌乳第6天和第18天宰杀；自由采食的非泌乳绵羊作为对照宰杀。尽管采食量增加，但泌乳母羊处于能量负平衡状态。泌乳使血浆瘦素和脂肪组织瘦素mRNA浓度降低。通过原位杂交测定，OB-Rb基因表达在泌乳两个阶段的下丘脑弓状核（ARC）和腹内侧下丘脑核（VMH）均增加。泌乳使ARC和下丘脑背内侧核（DMH）中的神经肽Y（NPY）增加，尽管DMH中基因表达增加仅在泌乳第18天明显。泌乳期间，ARC和VMH中可卡因和安非他明调节转录物（CART）以及ARC中阿黑皮素原的基因表达降低。ARC中刺鼠相关肽基因表达增加，泌乳时ARC和VMH中黑皮质素受体表达均无变化。因此，泌乳期的低瘦素血症可能激活下丘脑NPY促食欲途径，并减弱厌食性黑皮质素和CART途径，从而促进泌乳期的食欲亢进。
