O EXERCÍCIO FÍSICO E O CONTROLE SECRETOR DE INSULINA NA OBESIDADE INDUZIDA POR MARCAÇÃO METABÓLICA

Abstract

Developmental Windows are critical periods during the development of an organism,hormonal and nutritional interventions in this phase might predispose the organism to certain diseases in adulthood. These events are called imprinting or metabolic programming. The lactation period is considered one of the developmental Windows and changes in this phase might promote obesity and type 2 diabetes in adulthood. This study investigated the effects of regular physical activity on obesity induced by overnutrition in the lactation period and the insulin secretion control in isolated pancreatic islets. Litters of male Wistar rats were standardized to 10 offsprings per litter up to 3-day old, later the litters were readjusted to NN (normal litters) with 9 rats and NR (reduced litters) with 3 rats per litter. When the rats were 21 days old they were weaned and subdivided into sedentary (SED) and exercised (EXE) groups, forming 4 experimental groups: NNSED; NNEXE; NRSED and NREXE. The physical exercise program consisted of 3x/week/30 min. swimming. On the 90th day samples of fat tissue and pancreas were collected for histological analysis. Blood samples were collected for plasmatic biochemical analysis (glucose, triglycerides and cholesterol). The islets were isolated in different incubated glucose concentrations (8.3; 16.7; 20.0 and 28.0 mM) in the presence or absence of acetylcholine (Ach: 0.1; 1; 10; 100 and 1000 μm). The muscarinic receptor M3 and the PLCβ protein expressions were carried out in isolated pancreas islets. Data was expressed as average + average standard error, with variance analysis ANOVA (post Bonferroni test between the selected pairs) and Student’s Test t (p<0,05). NRSED animals developed obesity, with an increase of about 25% in visceral fat deposits. The fasting glucose increased 16.7% in this group without, however, affecting the remaining plasmatic parameters (cholesterol, triglycerides and insulin). White adipocytes and pancreas islets presented hypertrophy in the NRSED animals. Swimming reduced visceral fat deposits in 20% (NNEXE) and 12% (NREXE) and increased brown fat deposits in 106,8% (NN-EXE) and 63,9% (NR-EXE). Additionally, swimming reestablished the glycemia and prevented hypertrophy of white adipocytes and pancreas islets in NR-EXE animals. The pancreas islets of NR-SED rats presented reduction in the insulin secretion stimulated by glucose (33%) and Ach (104%). Islets of NR-EXE animals reestablished the glucose response without correcting the Ach action. The secretor effects were independent from the protein expression. However, in islets of NN-EXE group the lowest response to Ach was followed by the reduction (44.8%) in the M3 expression. Higher caloric intake promoted by the litter reduction during lactation favored obesity, besides leading to changes in the fat tissue and endocrine pancreas. Physical exercise can reduce obesity and reestablish insulin secretion following some stimuli.