An Early and Sustained Inflammatory State Induces Muscle Changes and Establishes Obesogenic Characteristics in Wistar Rats Exposed to the 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 induction of obesity upon systemic and muscular parameters of Wistar rats. The 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). Afterwards, 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, increased adiposity, and inducted hyperinsulinemia and a pro-inflammatory scenario. In adulthood, the following were observed: peripheral insulin resistance, increased fibrosis, oxidative distress, and a reduction in muscle mass, oxidative capacity, and neuromuscular junctions, increased fibrosis, and oxidative distress. Thus, we can conclude that the condition found in adult life and the difficulty restoring in the muscle profile is related to the metabolic damage established early on.

Investigating the Chemical Composition of Lepidium sativum Seeds and Their Ability to Safeguard against Monosodium Glutamate-Induced Hepatic Dysfunction

“…Multiple studies have demonstrated the links between MSG-induced obesity and other systems. Injections of MSG during the first seven days of a rat's existence led to MSGinduced obesity, which raised the mean arterial blood pressure and decreased heart rate variability, bradycardic responses, and vagal and sympathetic effects at 33 weeks relative to control rats [13]. The MSG-induced obesity model in mice demonstrated a significantly greater decrease in core temperature after acute exposure to cold (4 degrees Celsius for 2 h) and failed to mobilize brown adipose tissue lipids after exposure to 4 degrees Celsius for 6 h, whereas control animals did [14].…”

Multimodal Strategies to Fight Obesity: Research on Tailored Therapies Based on Natural and Synthetic Compounds for Prevention, Management and Treatment

“…Zazula et al demonstrated that an early and sustained inflammatory state favors the acquisition of persistent muscle changes and typical obesogenic features [ 21 ]. Such a study was performed via subcutaneous injection of monosodium glutamate (MNG) in Wistar rats.…”

“…The plasmatic profiles of the animals showed remarkable increases in glucose content, total cholesterol, LDL and VLDL, as well as in the amount of triacylglycerols. The analysis of muscle markers in MSG-treated rats provided evidence of an increase in lactate content and a decrease in creatine kinase with respect to the control group [ 21 ].…”