Chronic leucine supplementation does not prevent the obesity and metabolic abnormalities induced by monosodium glutamate

Abstract

Summary: Leucine (Leu) is an essential branched amino acid that regulates several aspects of metabolism and may have the ability to mitigate obesity and type 2 diabetes. In the present study, we evaluated the effect of chronic Leu supplementation on the obesity and metabolic abnormalities induced by neonatal monosodium l-glutamate (MSG) treatment. From the 2nd to 6th day after birth, male Wistar rats received MSG subcutaneously (4 g/kg/body weight) and Controls received saline. After weaning, rats were subdivided into 4 groups (n = 15/rats by group): Control-NS: non-supplemented lean rats; Control-Leu: lean rats that received Leu supplementation; MSG-NS: non-supplemented obese rats and MSG-Leu: obese rats that received Leu supplementation. Leucine (1.5%) was administered via drinking water for four months. Body weight, food and liquid intake were recorded during the duration of treatment and animals were euthanized at 120 days of life. Fat content, glucose homeostasis and glucose-induced insulin secretion (GIIS) were also evaluated. MSG-treated rats developed obesity, glucose intolerance, insulin resistance (IR), impaired GIIS and presented altered cholinergic responses. Despite promoting changes in the cholinergic response of isolated pancreatic islets, chronic Leu supplementation did not abrogate obesity or metabolic abnormalities, including IR and GIIS, in MSG-treated rats. Keywords: Amino acid, Obesity, Pancreatic islets, Metabolic dysfunction, Insulin secretion