Neural mechanisms of anti-stress effects of food intake

研究了食物摄入抗应激作用的神经机制PrRP（催乳素释放因子）在食物摄入和应激反应中的作用PrRP神经元由外周饱足因子CCK激活。PrRP诱导应激激素、ACTH、抗利尿激素和催产素的释放。因此，我们研究了PrRP在大鼠饱腹感和应激反应中的作用。用抗体中和内源性PrRP可增加每餐的进食量。在升高+迷宫试验中，静脉注射PrRP可减轻焦虑相关行为，而中和内源性PrRP可增强焦虑行为。内源性PrRP的中和降低了下丘脑室旁核Fos蛋白的表达，以及应激刺激下催产素的释放。这些数据表明，PrRP在食物摄入后的饱腹感和应激反应中起重要作用。瘦素和胃饥饿素在应激反应中的作用食物摄入增加血浆瘦素并降低胃饥饿素浓度。我们检测了应激刺激后，瘦素和胃饥饿素对下丘脑去甲肾上腺素释放和血浆ACTH浓度的影响。在应激刺激后，瘦素减弱下丘脑去甲肾上腺素释放和血浆ACTH浓度的增加，而胃促生长素则增强这些增加。这些数据表明，瘦素和胃饥饿素在食物摄入的抗应激作用中也起着重要作用。盐摄入量在应激反应中的作用压力会增加盐的摄入量。因此，我们研究了高渗刺激对应激反应的影响。血浆渗透压的增加减弱了下丘脑去甲肾上腺素释放的增加和应激刺激后血浆ACTH浓度的增加。这些数据表明，盐的摄入在应激反应中起抑制作用。这些数据表明，PrRP、瘦素、胃促生长素和血浆渗透压在食物摄入的抗应激作用中起重要作用。

Neural mechanisms of anti-stress effects of food intake were investigated.1 Roles of PrRP (prolactin-releasing factor) in food intake and stress responsesPrRP neurons are activated by the peripheral satiety factor, CCK. PrRP induces release of stress hormones, ACTH, vasopressin and oxytocin. We thus examined roles of PrRP in satiety and stress responses in rats. Neutralization of endogenous PrRP with antibodies increased amounts of food intake per meal. An icv injection of PrRP attenuated anxiety-related behaviour in an elevated plus maze test, while neutralization of endogenous PrRP augmented anxiety behavior. Neutralization of endogenous PrRP attenuated expression of Fos protein in the hypothalamic paraventricular nuclei, and oxytocin release in response to stressful stimuli. All these data suggest that PrRP plays an important role in satiety and stress responses after food intake.2.Roles of leptin and ghrelin in stress responsesFood intake increases plasma leptin and decreases ghrelin concentrations. We examined effects of leptin and ghrelin in noradrenaline release in the hypothalamus and plasma ACTH concentrations after stressful stimuli. Leptin attenuated increases in noradrenaline release in the hypothalamus and plasma ACTH concentrations following stressful stimuli, while ghrelin augmented these increases. These data suggest that leptin and ghrelin also play important roles in anti-stress effects of food intake.3.Roles of salt intake in stress responsesStress increases salt intake. We thus examined hyperosmotic stimuli upon stressful responses. An increase in plasma osmolality attenuated increases in noradrenaline release in the hypothalamus and plasma ACTH concentrations following stressful stimuli. These data suggest that salt intake plays an inhibitory role in stress responses.All these data suggest that PrRP, leptin, ghrelin and plasma osmolality play important roles in anti-stress effects of food intake.