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

Nikki Cassie, Richard Anderson, Dana Wilson, Julian G. Mercer, Perry Barrett* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)
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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.
Original languageEnglish
Pages (from-to)41-47
Number of pages7
JournalPhysiology and Behavior
Early online date26 Apr 2019
Publication statusPublished - 1 Aug 2019

Bibliographical note

This work was funded by the European Union Seventh Framework programme (Full4Health - grant number 266408) and the Scottish Government Rural and Environment Science and Analytical Services Division to the Rowett Institute. Funders had no role in the preparation of data or the manuscript


  • appetite
  • GLP-1
  • hindbrain
  • obesity
  • satiety
  • Appetite
  • Obesity
  • Satiety
  • Hindbrain


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