Eating elicited by orexin-A, but not melanin-concentrating hormone, is opioid mediated
Eating elicited by orexin-A, but not melanin-concentrating hormone, is opioid mediated
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DOI：
10.1210/en.143.8.2995
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发表时间：
2002-08-01
期刊：
影响因子：
4.8
通讯作者：
Seeley, RJ
中科院分区：
文献类型：
--
作者：
Clegg, DJ;Air, EL;Seeley, RJ
黑色素浓缩激素 (MCH) 和食欲素-A 是主要在外侧下丘脑产生的促进食欲的肽能神经递质。由于另外两种下丘脑肽（神经肽 Y 和刺鼠相关肽）通过依赖阿片受体激活的机制增加食物摄入，因此我们评估了 MCH 或食欲素-A 是否也通过阿片受体激活来引起食物摄入。纳洛酮（0.3 mg/kg，腹腔注射）剂量对其本身没有影响，却降低了第三心室（i3vt）食欲素-A（3 ng/大鼠）的急性食欲诱发作用。然而，相同剂量的纳洛酮对 i3vt MCH（5 杯/大鼠）诱导的食欲亢进没有影响。由于阿片类药物系统也与食物选择有关，因此我们研究了当大鼠同时接受两种脂肪和碳水化合物相对含量不同的饮食时，MCH 或食欲素-A 是否会改变食物选择。 i3vt MCH 刺激两种饮食的摄入并且不改变食物选择，而 i3vt 食欲素-A 只刺激高脂肪饮食的摄入。这些数据表明，尽管 MCH 和食欲素-A 之间有一些相似之处，但这两种下丘脑外侧区肽通过招募不同的神经回路来刺激食物摄入，并对食物选择产生不同的影响。
Melanin-concentrating hormone (MCH) and orexin-A are orexigenic peptidergic neurotransmitters produced primarily in the lateral hypothalamus. Because two other hypothalamic peptides, neuropeptide Y and agouti-related peptide, increase food intake by a mechanism that depends on activation of opioid receptors, we assessed whether MCH or orexin-A also elicits food intake via opioid receptor activation. A dose of naloxone (0.3 mg/kg, ip) that had no effect on its own reduced the acute orexigenic effect of third ventricular (i3vt) orexin-A (3 ng/rat). However, this same dose of naloxone had no effect on i3vt MCH (5 mug/rat)-induced hyperphagia. Because the opioid system has also been linked to food selection, we investigated whether MCH or orexin-A alters food choice when rats have simultaneous access to two diets differing in the relative amounts of fat and carbohydrate. Whereas i3vt MCH stimulated intake of both diets and did not alter food choice, i3vt orexin-A stimulated intake of only the high fat diet. These data indicate that despite several similarities between MCH and orexin-A, these two lateral hypothalamic area peptides stimulate food intake by recruiting different neural circuits and exert different effects on food choice.