Avaliação da microbiota intestinal de ratas Wistar submetidas a dieta hipercalórica

Abstract

Obesity is a chronic disease, associated with comorbidities such as diabetes mellitus II, which affects approximately one third of the world population. Obese individuals may present changes in the intestinal microbiota compared to normal individuals, mainly due to a diet rich in carbohydrates and fat. Most of the studies indicate as a consequence of diet-induced obesity a decrease in the ratio between the Bacteroidetes and Firmicutes phyla, however the results may be controversial in individuals of both sexes. The objective of the present study was to submit a group of Wistar female rats to the intake of a hypercaloric diet for the development of obesity, and then to evaluate the constitution of the intestinal microbiota as compared to the normal diet. Thirty non-obese and non-diabetic Wistar female rats were divided into two groups: group 1 (G1) – control group with 15 rats, fed with commercial ration and water ad libitum; and group 2 (G2) – test group with 15 rats, fed with hypercaloric modified ration and 20% fructose diluted in water, for 24 weeks. Growth parameters such as weight and Lee index were evaluated, as well as biochemical parameters such as oral glucose tolerance and glycemia. At the end of the experiment fecal samples were collected from the rectal ampulla of four rats from each group and the intestinal microbiota was evaluated by extraction of total DNA (ZR Fecal DNA MiniPrep kit – Zymo Research) and new generation sequencing of the 16S gene in a MiSeq sequencer (Illumina) and sequence analysis on the Quantitative Insights Into Microbial Ecology (QIIME) platform. In the obese rats, a significant increase of Firmicutes was observed in relation to the control group (83.51% versus 64.73%), whereas Bacteroidetes had a reduced proportion as a function of the treatment (20.47% versus 7.79%). Among the 242 bacterial genera identified, 14 represented more than 50% of the population and of these, 12 presented significant concentration differences between treatments. The genera Lactobacillus, Allobaculum and Clostridium were the most abundant in the microbiota of obese rats, whereas the genus Turicibacter was the most abundant in the control group. The treatment with hypercaloric diet decreased the diversity of bacterial genera in the intestinal microbiota.