CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division, Department of Medicine, at University of California Los Angeles and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California;
Am J Physiol Regul Integr Comp Physiol. 2014 Feb 1;306(3):R164-74. doi: 10.1152/ajpregu.00335.2013. Epub 2013 Dec 11.
Tail pinch stimulates food intake in rats. We investigated brain mechanisms of this response and the influence of repeated exposure. Sprague-Dawley rats received acute (5 min) or repeated (5 min/day for 14 days) tail pinch using a padded clip. Acute tail pinch increased 5-min food intake compared with control (0.92 ± 0.2 vs. 0.03 ± 0.01 g, P < 0.01). This response was inhibited by 76% by intracerebroventricular injection of BIBP-3226, a neuropeptide Y1 (NPY1) receptor antagonist, increased by 48% by astressin-B, a corticotropin-releasing factor (CRF) receptor antagonist, and not modified by S-406-028, a somatostatin subtype 2 antagonist. After the 5-min tail pinch without food, blood glucose rose by 21% (P < 0.01) while changes in plasma acyl ghrelin (+41%) and adrenocorticotropic hormone (+37%) were not significant. Two tail pinches (45 min apart) activate pontine and hindbrain catecholaminergic and hypothalamic paraventricular CRF neurons. After 14 days of repeated tail pinch, the 5-min orexigenic response was not significantly different from days 2 to 11 but reduced by 50% thereafter (P < 0.001). Simultaneously, the 5-min fecal pellet output increased during the last 5 days compared with the first 5 days (+58%, P < 0.05). At day 14, the body weight gain was reduced by 22%, with a 99% inhibition of fat gain and a 25% reduction in lean mass (P < 0.05). The orexigenic response to acute 5-min tail pinch is likely to involve the activation of brain NPY1 signaling, whereas that of CRF tends to dampen the acute response and may contribute to increased defecation and decreased body weight gain induced by repeated tail pinch.
尾巴夹捏会刺激老鼠进食。我们研究了这种反应的大脑机制以及重复暴露的影响。斯普拉格-道利大鼠接受急性（5 分钟）或重复（5 分钟/天，共 14 天）尾巴夹捏，使用带衬垫的夹子。急性尾巴夹捏与对照组相比增加了 5 分钟的食物摄入量（0.92±0.2 比 0.03±0.01 g，P<0.01）。该反应被脑室内注射神经肽 Y1（NPY1）受体拮抗剂 BIBP-3226 抑制了 76%，被促肾上腺皮质激素释放因子（CRF）受体拮抗剂 astressin-B 增加了 48%，而被生长抑素亚型 2 拮抗剂 S-406-028 没有改变。在没有食物的 5 分钟尾巴夹捏后，血糖升高了 21%（P<0.01），而血浆酰基 ghrelin（+41%）和促肾上腺皮质激素（+37%）的变化不显著。两次尾巴夹捏（间隔 45 分钟）激活脑桥和延髓儿茶酚胺能和下丘脑室旁 CRF 神经元。经过 14 天的重复尾巴夹捏后，5 分钟的食欲刺激反应与第 2 至 11 天没有显著差异，但此后减少了 50%（P<0.001）。同时，在最后 5 天，5 分钟的粪便颗粒排出量比前 5 天增加了 58%（P<0.05）。在第 14 天，体重增加减少了 22%，脂肪增加抑制了 99%，瘦体重减少了 25%（P<0.05）。急性 5 分钟尾巴夹捏的食欲刺激反应可能涉及大脑 NPY1 信号的激活，而 CRF 的反应则倾向于抑制急性反应，并可能导致重复尾巴夹捏引起的粪便排出增加和体重增加减少。
