Desenvolvimento de modelo de desnutrição em camundongos: avaliação comparativa do percentual de restrição alimentar e de diferentes dietas

Abstract

Malnutrition is a complex pathology, associated with increased risk of mortality, susceptibility to infectious diseases and impaired cognitive development. It is a global public health problem. Experimental models have been developed to understand the mechanisms involved in the pathology of malnutrition. However, due to limitations, there is no consensus in the literature about which murine model produces effects that mimic conditions in humans. Given the above, the present study aimed to validate a murine model of malnutrition, based on dietary restriction, using two types of diet, to characterize its effects on malnutrition. The study was conducted with fifty-six Swiss mice (eight-week-old males) divided into eight groups (n=7 each) and fed the following experimental diets for 10 weeks. The groups were divided into: Standard Diet (ST) ad libitum; ST 20% dietary restriction; ST 40% dietary restriction; ST60% dietary restriction; AIN93-M diet ad libitum; AIN93-M 20% dietary restriction; AIN93-M 40% dietary restriction; AIN93-M 60% dietary restriction. Body, biochemical and histological parameters were measured, in addition to evaluating the effects of restrictions with the AIN93-M diet on genes related to oxidative stress such as GPX1 and GPX4 in epididymal tissue in qRT-PCR. Given the results obtained, it is concluded that dietary restrictions of 20%, 40% and 60% were able to reduce body weight when compared to their controls, highlighting the accentuated weight loss in animals with restrictions of 60%, especially those fed with AIN-93 M. The 40% and 60% restriction protocols were able to reduce adiposity in two types of diets, as well as the area of adipocytes and the fat layer of the epididymal tissue, and again of significantly in groups with 60% dietary restriction. In this restriction group, fed with the AIN93-M diet, physical changes were observed, such as whitish skin and dull coat, voracious eating and hunched posture. The AIN93-M diet proved to be the best diet for carrying out this protocol. Through this model, it was possible to obtain a reduction in the animals' body weight, biochemical changes, such as in the lipid profile (decrease in HDL and triglycerides) and hypoalbuminemia, as well as histological changes in the epididymal adipose tissue. The presence of increased oxidative stress was observed in this restriction group, through the evaluation of the GPX4 gene. Given the above, food restriction of 60% with the Ain93-M diet was the best protocol for inducing malnutrition.