Effect of a high protein diet from a vegetal and animal source on the Microbiota-Gut-Brain axis in a murine model

Abstract

The gut-brain axis is a complex bidirectional communication system that allows an intimate connection between both organs through different mechanisms. Recent studies regarding the gut microbiota now support its prominent role in modifying behavior and cognition. As consequence, there has been a growing interest in studying various dietary strategies to modulate behavior targeting the gut microbiota. High protein diets, both of plant and animal origin, have become popular as a dietary intervention due to their beneficial effects on metabolism; however, in high amounts, harmful effects on the intestinal microbiota can occur, so this type of diet is still a matter of debate. The present work aims to investigate whether diets high in protein from either plant or animal origin are capable of inducing changes in the gut-brain axis in a murine model. Thirty C57BL/6 mice were assigned to three treatment groups (n = 10 per group) and were fed a normal control diet (NC) or hyper-protein diets of plant (HPV) or animal (HPA) origin for 8 weeks, being monitored by weight, behavior and composition of the microbiota. The behavior analysis was carried out at the end of the dietary intervention using three behavioral tests: elevated plus maze test, 'Y' shaped maze, and forced swimming test. Different levels of activity with statistical significance (p<0.05) were present in all tests, except from the ‘Y’ shaped maze. Following dietary intervention, changes in the concentration of Lactobacillus, Bifidobacterium (p<0.05) and Enterobacteriaceae (p<0.05) were measured by quantitative PCR. Contrastingly, a significant reduction in the concentration of short chain fatty acids (p<0.05) was found on the luminal contents of mice, a measurement done via Gas Chromatography. The results of this research will allow to make more careful recommendations in the undertaking of dietary interventions with a greater contribution of protein in relation to other macronutrients.