Effects of physical exercise on glycemic metabolism, aerobic capacity and structure of brown adipose tissue in diabetic animals

The ability of brown adipose tissue (BAT) and aerobic physical exercise (AET) to improve energy metabolism is widely known. Since AET has been used as an insulin- sensitizing therapy for diabetes, here we tested whether the effects of AET on the glycemic metabolism and aerobic capacity of diabetic animals are accompanied by structural changes in BAT. Adult male C57BL6/J mice were assigned into groups: non-diabetic sedentary (NDS, n=6), non-diabetic trained (NDT, n=6), diabetic sedentary (DS, n=4) and diabetic trained (DT, n=7). Diabetes was induced by high-fat and -fructose diet and intraperitoneal injection of streptozotocin (120 mg/g). AET consisted of 8-wk running session of 60 min at 60% of maximal speed, 5 days/wk. Experimental procedures were approved by Ethics Committees from Faculty of Medicine and from School of Arts, Science and Humanities of University of São Paulo (#1473/2020 and #001/2020, respectively). Initial body weight (BW) did not differ among groups, however the DS and DT groups had lower final BW compared with NDS. The BW gain of DS group was lower compared with NDS group. Food consumption (Kcal/animal/day) was higher in DT group compared with NDS and NDT. The DS and DT groups had higher fasting blood glucose, and DS group had greater area under the curve on the glucose tolerance test than the NDS and NDT groups. Indirect calorimetry measurement at rest revealed no difference in the variables oxygen uptake (VO2), carbon dioxide expiration (VCO2), respiratory exchange ratio (RER), energy expenditure (EE), carbohydrate and fat oxidation among groups. During maximal exercise test, NDT and DT increased the time to exhaustion, maximal speed, intensity corresponding to the VO2máx (iVO2) compared with NDS and DS. An increase in VO2máx and VCO2máx was observed in NDT group compared with DS and DT group. No differences were observed in the weight of white adipose tissue depots (retroperitoneal, periepididymal and subcutaneous), interscapular brown adipose tissue (iBAT), skeletal muscle (gastrocnemius and soleus), and other organs (heart, lung, and kidney). Morphometric analysis of the iBAT revealed that the area, diameter, volume, mass, frequency of lipid droplet distribution by size (small, medium, large, and very large) and amount of lipid droplets did not differ among groups, however, collagen deposition in the iBAT increased in the DS and DT groups compared with NDS group. In conclusion, the AET-induced improvement in glucose tolerance and aerobic capacity in diabetic animals is not accompanied by changes in morphometry and collagen deposition in the iBAT. This study was supported by grants from the São Paulo Research Foundation (FAPESP) #2020/15748-4 and #2020/12005-0. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.