Perfil nociceptivo e inflamatório de ratos com obesidade induzida por dieta hipercalórica

Abstract

Although obesity can lead to changes in pain threshold, the mechanism by which this occurs is not well understood. With the recent discoveries of the properties of white adipose tissue to secrete substances with important biological effects, endocrine role has assumed greater importance. The occurrence and magnitude of pain and inflammation may be related to endocrine changes caused by obesity, among which we highlight the changes in the levels of inflammatory cytokines, leptin, ghrelin and endogenous opioids, among others. For this reason, the objective of this study was to evaluate, through tests of acute nociception, such as Hot Plate, Tail Withdrawal, electronic Von Frey test and evaluation of Paw Edema by Pletismometry, differences in nociceptive threshold and inflammatory profile, between animals that had high-calorie diet-induced obesity (HD group) and animals fed a control diet (CD) from the fourth week of life, for 16 weeks. In addition, behavioral tests were also performed, such as Elevated Plus Maze and Open Field test to evaluate anxiety and movement in the apparatus, between the groups. Metabolic parameters, such as Lee Index, fasting glucose, triglycerides and serum proteins were evaluated and perigonadal and retroperitoneal fat were excised and weighed to the characterization of experimental obesity in both groups. Our results demonstrate that metabolic parameters and weight of perigonadal and retroperitoneal fat were higher in HD than in group CD, showing that high calorie diet was effective in inducing obesity in the HD group. In tests of acute nociception, the Tail Withdrawal showed no difference between groups, while in the Hot Plate test, the HD group showed a shorter latency period in seconds for the CD group reaction after application intraplantar carrageenan compared the control group (saline). It was also shown that animals of the HD group had a greater mechanical hypernociception and a grea paw edema after carrageenan application. In the assessment of behavioral tests were not significant differences between groups. The experiments were conducted at the Institute of Biological Sciences, Federal University of Alfenas.