Efeitos de dois protocolos de jejum intermitente versus modificação dietética ou exercícios na microcirculação e na composição corporal de hamsters alimentados com ração hiperlipídica

Abstract

Abnormal or excessive accumulation of adipose tissue with potential damage to health is defined by the World Health Organization (WHO) as obesity. Adipose tissue is recognized as an active endocrine organ and, in obesity, elicits microvascular dysfunction and increases the incidence of cardiovascular diseases, with high morbidity and mortality. Studies in rodents and humans have highlighted the importance of feeding frequency and the effects of fasting periods in reducing obesity, and in the prevention and treatment of diseases, through reprogrammation of metabolic pathways. Our aim was to investigate the effects of intermittent fasting on microcirculation and cardiometabolic variables in hamsters with overweight, comparing the results with conventional dietary modification (continuous caloric restriction) and treadmill training (chronic aerobic exercise). Male hamsters (Mesocricetus auratus) were fed for 12 weeks with standard (commercial chow) or high fat diet, delivered 21 days after birth. From week 12 to 20, the animals were distributed into 7 groups: 1) CT (control fed with standard chow); 2) CTEX (control associated with moderate chronic aerobic exercise 5 times a week); 3) HL (high fat diet); 4) HLRC (modification from high fat diet to standard chow); 5) HLJP (high fat diet with fasting for 48 consecutive hours per week); 6) HLJA (high fat diet with fasting for 24 hours on 2 alternate days per week); 7) HLEX (high fat diet with moderate chronic aerobic exercise 5 times a week). Body composition was analyzed by dual-energy X-ray absorptiometry (DEXA); the microvascular macromolecular permeability was assessed in the hamster's cheek pouch preparation and the expression of endothelial (eNOS) and inducible (iNOS) nitric oxide synthases, in the left ventricular cardiac muscle and in the thoracic aorta, was assessed by immunoblotting. We observed that high fat feeding promoted an increase in total body mass and adipose tissue, a reduction in lean mass and an increase in microvascular permeability after ischemia-reperfusion. Periodic intermittent fasting (HLJP) resulted in a reduction in body mass and adipose tissue similar to the conventional diet of continuous caloric restriction (HLRC), while alternate day intermittent fasting (HLJA) and physical exercise (HLEX) did not exhibit the same effect. The intermittent fasting protocols do not seem to alter the lean mass of the animals fed with high fat diet. In addition, alternate day fasting (HLJA) recovered the microvascular function by decreasing macromolecular permeability. No significant differences were found in the tissue expression of iNOS or eNOS. Therefore, our findings suggest that the frequency of fasting (on 2 alternate days) seems to restore microcirculatory permeability altered by fat overload, while the duration of fasting (for 48 consecutive hours) seems to improve body composition in hamsters fed with high fat diet