Early and Sustained Inflammatory State Induces Muscle Changes and Establishes Obesogenic Characteristics in Wistar Rats Exposed to MSG-Induced Obesity Model

Abstract

The model of obesity induced by monosodium glutamate cytotoxicity on the hypothalamic nuclei is widely used in the literature. However, MSG promotes persistent muscle changes and there is a significant lack of studies that seek to elucidate the mechanisms by which damage refractory to reversal is established. This study aimed to investigate the early and chronic effects of MSG in-duction of obesity upon systemic and muscular parameters of Wistar rats. Animals were exposed to MSG subcutaneously (4 mg.g-1 b.w.) or saline (1.25 mg.g-1 b.w.) daily from PND01 to PND05 (n = 24). After, in PND15, 12 animals were euthanized to determine the plasma and inflammatory profile and to assess muscle damage. In PND142, the remaining animals were euthanized, and samples for histological and biochemical analyses were obtained. Our results suggest that early exposure to MSG reduced growth, and increased adiposity, induction hyperinsulinemia, and a pro-inflammatory scenario. In adulthood were found, peripheral insulin resistance, reduced muscle mass, oxidative capacity, neuromuscular junctions, increased fibrosis, and oxidative distress. Thus, we can conclude that the condition found in adult life and the difficulty in restoring the muscle profile are related to the metabolic damages established early.