Rowett Institute, University of Aberdeen, Foresterhill Campus, Aberdeen AB25 2ZB, UK.
Rowett Institute, University of Aberdeen, Foresterhill Campus, Aberdeen AB25 2ZB, UK.
Physiol Behav. 2019 Aug 1;207:41-47. doi: 10.1016/j.physbeh.2019.04.022. Epub 2019 Apr 26.
This study aimed to determine the relative efficacy of the macronutrients, protein, fat and carbohydrate to induce satiation and satiety in rats in relation to macronutrient activation of neurons in the nucleus of the solitary tract (NTS). Male Sprague Dawley rats were schedule-fed twice a day for 2 h, receiving 100% of daily ad-libitum energy intake. On test day 1, 30 min before the first scheduled meal of the day, rats were gavaged with an 8 kcal isocaloric, isovolumetric solution of a glucose, lipid or peptone macronutrient solution or a non-caloric saline solution. To assess satiation, thirty minutes later rats were given access to food for 2 h and food intake determined. A second 2 h food access period 3 h later was used for assessment of satiety. On the second test day, rats were gavaged as before and killed 90 min after food presentation. Blood was collected for measurement of circulating metabolic markers. Brains were removed for analysis of c-Fos expression by in situ hybridization in the NTS. Rats which received saline consumed a similar amount of food compared to pre-gavage intakes. However, rats gavaged with a caloric macronutrient solution all reduced food intake by 18-20 kcal. Interestingly, the reduction in caloric intake was greater than the caloric value of the macronutrient solution gavaged and was sustained following the second scheduled meal. Quantification by in situ hybridization of c-Fos mRNA expression in the NTS 90 min post-gavage, showed a significant increase with each macronutrient, but was 24-29% higher with a lipid or peptone gavage compared to a glucose gavage. In conclusion, when delivered directly to the stomach, all macronutrients can be equally effective in inducing satiation with significant neuronal activation in the NTS of the hindbrain.
本研究旨在确定蛋白质、脂肪和碳水化合物等宏量营养素在诱导大鼠饱腹感方面的相对功效，并探讨其与孤束核（NTS）神经元中宏量营养素激活的关系。雄性 Sprague Dawley 大鼠每天分两次喂食 2 小时，给予 100%的每日自由摄入量。在测试的第一天，在当天的第一顿预定膳食前 30 分钟，大鼠通过灌胃给予等热量等容积的葡萄糖、脂质或蛋白胨宏量营养素溶液或非热量生理盐水溶液。为了评估饱腹感，30 分钟后，大鼠可以进食 2 小时，并确定食物摄入量。3 小时后，进行第二个 2 小时的进食时间段，用于评估饱腹感。在第二个测试日，大鼠按照之前的方式灌胃，并在进食后 90 分钟处死。收集血液用于测量循环代谢标志物。取出大脑，通过原位杂交分析 NTS 中的 c-Fos 表达。接受生理盐水的大鼠与灌胃前的摄入量相比，消耗了相似量的食物。然而，接受热量宏量营养素溶液灌胃的大鼠的食物摄入量均减少了 18-20 卡路里。有趣的是，热量摄入的减少大于灌胃的宏量营养素溶液的热量值，并且在第二个预定膳食后仍然持续。灌胃后 90 分钟，通过原位杂交对 NTS 中的 c-Fos mRNA 表达进行定量，发现每种宏量营养素均显著增加，但与葡萄糖灌胃相比，脂质或蛋白胨灌胃时增加了 24-29%。总之，当直接输送到胃部时，所有宏量营养素都可以同样有效地诱导饱腹感，并在脑桥的 NTS 中引起显著的神经元激活。
