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Protein Appetite Drives Macronutrient-Related Differences in Ventral Tegmental Area Neural Activity

Authors
  • Chiacchierini, Giulia
  • Naneix, Fabien
  • Peters, Kate Zara
  • Apergis-Schoute, John
  • Snoeren, Eelke Mirthe Simone
  • McCutcheon, James Edgar
Type
Published Article
Journal
Journal of Neuroscience
Publisher
Society for Neuroscience
Publication Date
Jun 09, 2021
Volume
41
Issue
23
Pages
5080–5092
Identifiers
DOI: 10.1523/JNEUROSCI.3082-20.2021
PMID: 33926995
PMCID: PMC8197647
Source
PubMed Central
Keywords
Disciplines
  • Research Articles
  • Behavioral/Cognitive
License
Unknown

Abstract

Control of protein intake is essential for numerous biological processes as several amino acids cannot be synthesized de novo, however, its neurobiological substrates are still poorly understood. In the present study, we combined in vivo fiber photometry with nutrient-conditioned flavor in a rat model of protein appetite to record neuronal activity in the VTA, a central brain region for the control of food-related processes. In adult male rats, protein restriction increased preference for casein (protein) over maltodextrin (carbohydrate). Moreover, protein consumption was associated with a greater VTA response, relative to carbohydrate. After initial nutrient preference, a switch from a normal balanced diet to protein restriction induced rapid development of protein preference but required extensive exposure to macronutrient solutions to induce elevated VTA responses to casein. Furthermore, prior protein restriction induced long-lasting food preference and VTA responses. This study reveals that VTA circuits are involved in protein appetite in times of need, a crucial process for animals to acquire an adequate amount of protein in their diet. SIGNIFICANCE STATEMENT Acquiring insufficient protein in one's diet has severe consequences for health and ultimately will lead to death. In addition, a low level of dietary protein has been proposed as a driver of obesity as it can leverage up intake of fat and carbohydrate. However, much remains unknown about the role of the brain in ensuring adequate intake of protein. Here, we show that in a state of protein restriction a key node in brain reward circuitry, the VTA, is activated more strongly during consumption of protein than carbohydrate. Moreover, although rats' behavior changed to reflect new protein status, patterns of neural activity were more persistent and only loosely linked to protein status.

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