Avaliação dos efeitos do Light Emitting Diode (LED) de baixa intensidade no tecido adiposo branco e marrom de camundongos obesos

Abstract

Obesity is one of the most relevant public health problems worldwide. It is a multifactorial disease that involves genetic, epigenetic, and environmental factors, being characterized by increased weight and/or body adiposity. The proposition of prevention, control and treatment strategies for obesity are urgent and necessary to minimize this disease’s impacts on the individual’s quality of life and health services. The use of photobiomodulation therapies arises as a promising field for diverse diseases. In the obesity context, however, little evidence on this technique's role is given, especially using a Light-Emitting Diode (LED). Therefore, the present study aimed to evaluate the effects of LED irradiation on the expression of thermogenesis and lipogenesis-associated markers in the brown and white adipose tissue, respectively, and on the body, metabolic and histological parameters in mice with obesity induced by a hyperglycemic diet. The experiment was performed with 24 mice divided into four groups: i) standard group (ST) fed with hyperglycemic diet; ii) HCD group fed with hyperglycemic diet; iii) LED+I group fed with hyperglycemic diet and exposed to LED irradiation in the dorsal region (interscapular); iv) LED+A group fed with hyperglycemic diet and exposed to LED irradiation in the abdominal region. The first phase of the study comprehended the induction of obesity for 12 weeks. Next, the animals of the LED+I and LED+A groups were submitted to LED irradiation sections on the following days: 1, 3, 7, 10, 14, and 21. Body, biochemical and histological parameters, along with the expression thermogenesis and lipogenesis-associated markers were assessed in the adipose tissue via qRT-PCR. The main findings pointed to an increased body weight variation (final body weight minus initial body weight) between the HCD and LED+A groups. Furthermore, it was observed a 33.3% and 23.8% reduction in the epidydimal adipose tissue weight, and 25% and 10.7% in the visceral adiposity in the LED+I and LED+A groups, respectively, as compared to HCD, although without statistically significant association as established by the p-value cutoff set as < 0.05. The qualitative histological evaluation of the epidydimal and brown adipose tissue pointed to decreased accumulation of fat droplets in the treated groups as compared to HCD. Finally, the LED exposition was associated with an increased mRNA expression of the uncoupling protein 1 – UCP1 in the brown adipose tissue and decreased fatty acid synthase – FAS in the epidydimal adipose tissue. Altogether, these findings suggest that the LED treatment promoted improvements in the body parameters, which is possibly associated with the histological alterations and thermogenesis and lipogenesis markers expression modulation in the white and brown adipose tissue, respectively.