Pickavance L, Dryden S, Hopkins D, Bing C, Frankish H, Wang Q, Vernon R G, Williams G
Department of Medicine, University of Liverpool, England.
Peptides. 1996;17(4):577-82. doi: 10.1016/0196-9781(96)00018-6.
NPYergic neurons in the hypothalamic arcuate nucleus (ARC) that project to the paraventricular nucleus (PVN) are postulated to regulate food intake and energy balance. This projection is overactive in lactation and is thought to drive hyperphagia in this condition. We have explored further the relationship between hypothalamic NPY and food intake in lactation and tested the hypothesis that hypoinsulinemia is the stimulus to NPY neuronal activity. Compared with nonlactating controls (n = 10), freely fed lactating rats (n = 9) showed significantly increased (p < 0.05) NPY levels in the ARC and medial preoptic area (MPO), but there was no significant increase in whole hypothalamic NPY mRNA levels. Lactating rats (n = 8) that were restricted to control rats' food intake for 3 days showed generally higher hypothalamic NPY levels, with significantly higher concentrations than controls (p < 0.05) in the ARC, MPO, PVN, and lateral hypothalamic area (LHA); NPY mRNA levels were also significantly increased (p < 0.05). Across all three experimental groups, there was a significant inverse correlation between plasma insulin concentration and hypothalamic NPY mRNA levels (r = -0.39, p < 0.01). We conclude that the ARC-PVN projection is overactive in lactation and that this is not a consequence of hyperphagia. Hypoinsulinemia may stimulate these neurons, as it is thought to do in other conditions of energy deficit.
下丘脑弓状核（ARC）中投射至室旁核（PVN）的神经肽Y（NPY）能神经元被认为可调节食物摄入和能量平衡。这种投射在哺乳期过度活跃，被认为会导致哺乳期的摄食亢进。我们进一步探讨了下丘脑NPY与哺乳期食物摄入之间的关系，并检验了低胰岛素血症是NPY神经元活动刺激因素这一假说。与非哺乳期对照组（n = 10）相比，自由进食的哺乳期大鼠（n = 9）的ARC和内侧视前区（MPO）中的NPY水平显著升高（p < 0.05），但整个下丘脑的NPY mRNA水平没有显著升高。将哺乳期大鼠（n = 8）限制在对照组大鼠的食物摄入量水平3天，其下丘脑NPY水平总体上较高，ARC、MPO、PVN和下丘脑外侧区（LHA）中的浓度显著高于对照组（p < 0.05）；NPY mRNA水平也显著升高（p < 0.05）。在所有三个实验组中，血浆胰岛素浓度与下丘脑NPY mRNA水平之间存在显著的负相关（r = -0.39，p < 0.01）。我们得出结论，ARC - PVN投射在哺乳期过度活跃，且这并非摄食亢进的结果。低胰岛素血症可能刺激这些神经元，就像在其他能量缺乏情况下一样。
