Efeito da vagotomia subdiafragmática e seletiva sobre a morfofisiologia do tecido adiposo de camundongos obesos

Abstract

Obesity has taken on alarming proportions all over the world, being considered an important economic and global health problem. Among the health problems caused by obesity are type 2 diabetes mellitus, fatty liver disease, cardiovascular problems and various types of cancer. Although several factors may be involved in the development of obesity, evidence indicates that a dysfunction in the autonomic nervous system (ANS) contributes to the accumulation of adipose tissue and to the maintenance of this syndrome. The parasympathetic nervous system, via the vagus nerve, innervates abdominal visceral organs and is involved in many necessary functions for metabolic homeostasis. Hyperinsulinemia is a frequent abnormality in the establishment and development of obesity. Experimental evidence suggests that an ANS dysfunction, with increased parasympathetic activity and reduced sympathetic activity, may lead to increased insulin secretion and β-cell mass, which contributes to body fat accumulation and maintenance of obesity. Studies have shown that bilateral subdiaphragmatic vagotomy normalizes plasma insulin concentration and glucose tolerance, in addition to decreasing fat accumulation in morbidly obese patients. Based on this evidence, we investigated the participation of the PSNS, through subdiaphragmatic and selective vagotomy, in energy metabolism, insulin secretion and food intake in obese mice. For this purpose, approximately 52 male mice of the C57BL6 lineage, 40 days old, were divided into two groups: the control group (CTL) received a standard diet for laboratory animals and the obese group (OB) received a high-fat diet (HFD). After eight weeks of HFD diet and obesity induction, surgical procedures were performed, forming the following groups: 1) OB-Sham-operated Group (OB-Sham); 2) OB-Selective Vagotomy Group (OB-VagS) and 3) OB-Total Subdiaphragmatic Vagotomy Group (OB-VagT). After eight weeks of the surgical procedures, the OB-VagT animals showed a reduction in body weight and lean mass, along with a decrease in brown adipose tissue (BAT) stores. Total vagotomy did not change glucose and plasma insulin levels, but normalized total cholesterol levels. Selective vagotomy was not effective in the weight loss of the animals, however, it altered daytime food intake and increased the number of adipocytes and lipid inclusions per field in the BAT, showing similarities to that found in the OB-VagT group.