Mitochondrial Respiration and Morphological Alterations in Different Adipose Tissues in Rats Treated with a High-Fat Diet and a Single Low-Dose Streptozotocin Injection or a Fructose Solution

In a 24-week-long experiment, 31 rats were assigned to one of 3 groups: a Control group receiving standard chow and water, a Fructose group receiving standard chow and a 20% fructose solution, or an STZ+lipids group that received a fat-enriched diet following a single 25 mg/kg streptozotocin injection at the onset of the diet. Both groups experienced significantly increased caloric intake but did not gain weight above the Control group level. Adipocytes in subcutaneous and visceral adipose depots of both groups had smaller size compared to control and higher density in tissue. Respirometric analyses unveiled a substantial increase in mitochondrial respiration across all adipose tissue types in both dietary intervention groups, with greater changes observed in the Fructose group. Correlation analyses demonstrated that in both experimental groups high tissue respiration is associated with better biochemical profile and closer to control adipose tissue morphology. Increased tissue respiration in adipose depots could be an important mechanism of resilience to excessive caloric intake.