Efeito do consumo crônico do adoçante natural stévia (S. Rebaudiana Bertoni) sobre parâmetros metabólicos e atividade mitocondrial do fígado de camundogos obesos hiperalimentados durante a lactação

Abstract

Obesity and overweight are defined as an excessive accumulation of body fat that can be harmful to health, being directly related to the increased prevalence and severity of non-alcoholic fatty liver disease. An important mechanism that can cause obesity is metabolic programming, a phenomenon that modulates crucial adjustments that can predispose to obesity in adulthood. Due to the need to lose and control body weight, the consumption of sweeteners, has increased worldwide. Stevia rebaudiana Bertoni is a plant native to South America that has a high sweetening power, which is why it is used in the production of the natural sweetener stevia. Recent experimental studies in vivo and in vitro have shown that stevia has antioxidant and anti-inflammatory properties. Our objective, therefore, was to evaluate the effect of the consumption of the sweetener stevia on the endocrine-metabolic response and the mitochondrial function of the liver of obese adult mice submitted to overfeeding during lactation. To induce overfeeding, Swiss mouse litters were reduced to 3 male pups per lactating woman on the 3rd day of postnatal life (overfed group - OG). Control litters were adjusted to 9 pups per infant (control group - CG). At 90 days of life, the control and overfed groups were divided into two subgroups, a control and overfed group that received water containing 0.3% stevia (CG-ST and OG-ST) or a control and overfed group that received pure water ( CG-AG and OG-AG). The animals were euthanized at 180 days of life. We evaluated food and water consumption by the animals throughout the study. Body composition was measured by nuclear magnetic resonance and we verified the weight of some tissues such as liver, brown adipose tissue and retroperitoneal fat. We measured the serum insulin concentration and, by Western Blotting, we quantified the content of GLUT-2, IRS-1 and PI3K. We analyzed the catalase activity and the formation of TBARS, for the analysis of hepatic oxidative stress. Mitochondrial metabolism was analyzed by high-resolution respirometry. Our data show that overnutrition during lactation induces an increase in body fat and tissue weight such as liver, heart fat, brown adipose tissue and retroperitoneal fat, in addition to inducing hyperinsulinemia. We observed that stévia intake was able to decrease food consumption and cause an addictive effect in GH-ST animals, in addition, GH-ST released greater amounts of insulin into the blood, generating a compensatory effect to capture a greater amount of glucose and also showed a significant increase in the maximum respiratory rate stimulated by ADP. However, stévia did not alter the balance between antioxidants and reactive oxygen species, nor in the proteins analyzed in Western Blotting. We conclude that overnutrition during lactation promotes morphological and metabolic changes and that the chronic consumption of sweetener stévia promotes distinct metabolic changes according to the nutritional status of the animal, reducing food intake, increasing glucose uptake and mitochondrial function in overfed animals. However, we suggest that more studies be carried out to better clarify the possible medicinal effects of stevia in peripheral tissues, such as the liver.