Fat, carbohydrate and protein by oral gavage in the rat can be equally effective for satiation

Abstract

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 2h, receiving 100% of daily ad-libitum energy intake. On test day 1, 30min before the first scheduled meal of the day, rats were gavaged with an 8kcal 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 2h and food intake determined. A second 2h food access period 3h later was used for assessment of satiety. On the second test day, rats were gavaged as before and killed 90min 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 18-20kcal. 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 minutes 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.

Exploring the Impact of Extra Virgin Olive Oil on Maternal Immune System and Breast Milk Composition in Rats

“…During this period, both the ROO and EVOO groups exhibited a reduction in weight compared to the REF group. These results, showing that rats subjected to lipid supplementation weigh less, are in line with previous research indicating that the oral administration of macronutrients, such as the oil in this study, can induce a sense of satiety [ 20 ], which in turn can affect the food intake and final body weight [ 40 ]. The animals in these groups also exhibit a reduced food intake, thus confirming this mechanism as a potential consequence of this satiety.…”

Transfer with microbiota from lean donors prevents excessive weight gain and restores gut-brain vagal signaling in obese rats maintained on a high fat diet

“…These satiation and satiety signals are known to be compromised, i.e., blunted, in HF feeding and obesity as a result of decreased sensitivity to CCK (10). Post-prandial vagal activation is dependent on the amount of kcal consumed as well as macronutrient makeup, with fat consumption leading to greater activation, for the same amount of kcal, than carbohydrates and proteins (76). There were no differences in the number of CART + neurons in the NG and c-Fos + neurons in the NTS following refeeding between HF-HF rats and LF animals, despite the HF-HF rats consuming a fat rich meal.…”

Post-oral sensing of fat increases food intake and attenuates body weight defense

“…This consumption may have created a ''binge''-like phenotype rather than the typical meal pattern seen in mice placed on an ad libitum HFD (Davis et al, 2021;Hatori et al, 2012). The relatively large binge eating of a HFD may have had a satiating effect (Cassie et al, 2019;Maljaars et al, 2008), i.e., a preload of HFD given in one dose may suppress food intake. Our results and this study both agree that intake and body weight increase with fat content on an ad libitum diet and are driven by hedonic signals (Licholai et al, 2018).…”

“…But, in addition to the oral sensing of components that contributes to palatability, mice can sense carbohydrate or fat content by post-oral mechanisms. An infusion of sucrose or fat directly into the stomach, thereby bypassing orophyrangeal sensing of taste and smell, can condition a preference in response to macronutrients (Ackroff and Sclafani, 2014;Cassie et al, 2019;Sclafani, 2001;Su et al, 2017;Tan et al, 2020;Zukerman et al, 2011Zukerman et al, , 2013. Although the ability to taste fat has been debated, the oropharyngeal sensing of fat, i.e., smell and texture, has been implicated in the ability of palatable high-fat foods to increase long-term food intake and body weight in rodents and humans (Ackroff and Sclafani, 2014;Corbit and Stellar, 1964;Massiera et al, 2010).…”