Avaliação fisiológica, comportamental e de expressão gênica do receptor GABA A no hipotálamo dorsomedial em resposta ao estresse em ratos obesos

Abstract

Obesity and stress are directly related to cardiovascular diseases. During stress there is an increase in cardiac output, blood pressure and body temperature. The dorsomedial hypothalamus (DMH) is essential for the integration of physiological and behavioral responses to emotional stress and anxiety disorders. The involvement of DHM in anxiety disorders and stress is related to hypothalamic reduction in GABAergic neurotransmission. However, the mechanism that causes neurotransmission impairment in obese rats is not known. Thus, the objective was to evaluate the effects of obesity on acute stress response in rats in the variables heart rate(HR), internal body temperature (IBT), anxiety and panic state, and level of GABAA receptor gene expression compared to non-obese rats. For this, Wistar rats were fed a control diet (Nuvilab®) or Hyperlipid Diet (HD) 45% Kcal / g lipid, both for nine weeks. Then, sensors were implanted to obtain values of HR and IBT.After seven days of recovery, values were recorded for 20 min of baseline time of all animals, 30 min during social stress by intruding rat in the animals of the control group submitted to stress (CE) and obese subject to stress (OE) , 30 min in animals that were not submitted to stress, control not submitted to stress (CNE) and obese without stress (ONE) and 30 min final for all. At the same time, infrared photographs were taken to evaluate the temperature of the tail and the back region of the animals.Subsequently, the time of stay in the elevated t- maze (ETM) and the number of quadrants traveled in the open field (OF) in CS and OS animals were evaluated.RNA from the HDM tissues of all animals were extracted, followed by RT-PCR and qPCR for analysis of the gamma-aminobutyric acid receptor (GABA) delta subunit gene expression. DH was efficient in inducing obesity through a significant increase in weight gain, fat mass, adiposity index, white adipose tissue epididimal, retroperitoneal, inguinal and brown adipose tissue of obese animals compared to control animals.The results showed that obese animals submitted to stress showed increased HR, IBT, tail temperature. In the behavioral tests, the obese animal showed an increase in the first exposure to the closed arm (anxiety-like behavior). The groups did not differ in relation to the panic-like behavior and the CA test. The level of gene expression of the delta subunit of the gamma-aminobutyric acid receptor was not altered between the groups. The present study collaborates with the literature investigating simultaneously the parameters of the HR, IBT, tail temperature, temperature of the back and behavioral in obese animals submitted to stress.