Name: DANIEL SESANA DA SILVA
Publication date: 04/04/2024
Examining board:
Name |
Role |
|---|---|
| ANDRE SOARES LEOPOLDO | Advisor |
Summary: Abstract: Introduction: Obesity is a chronic metabolic condition associated with increased morbidity and mortality. Although physiologically regulated, obesity is influenced by genetic, brain, metabolic, microbiome, and behavioral factors. Animal models, such as high-fat diet-induced obese (DIO) rats, have been used to understand its pathophysiology. These models reveal differences between obesity-prone (POb) and obesity-resistant (ROb) phenotypes, highlighting increased inflammation and comorbidity risk in POb. However, ROb exhibit lower body mass gain and higher levels of physical activity, suggesting a more efficient energy metabolism. It is important to note the need for further studies with consistent results to understand the relationship between phenotypes, energy metabolism, physical activity, and physical performance. Objective: To characterize the metabolic adaptations and physical performance of obesity-prone and obesity-resistant rats. Methods: Wistar rats (30 days old) were subjected to 23-week obesity exposure protocols. Initially, rats were randomized into two groups: a) SD: fed a standard diet (n = 39) and b) HFD: fed a high-fat diet (n = 39). Subsequently, animals were classified by tertile and characterized as POb and ROb on their respective diets. SD-ROb (n=13); SD-POb (n=13); HFD-POb (n=13); HFD-ROb (n=13). Ponderal, nutritional, metabolic, and adiposity parameters were analyzed. Basal metabolism assessment was performed using indirect calorimetry techniques. Insulin, glucagon, and leptin hormone levels were measured by ELISA. Physical performance and aerobic capacity were determined through treadmill exercise tests with gas analyzers for maximal oxygen consumption (VO2) and respiratory quotient (RQ) measurement. Results: The results showed that rats fed HFD exhibited a significant increase in body mass compared to those fed a standard diet, with a significant increase in food intake and caloric consumption after the experimentais diets exposure. Throughout the study, after group redistribution, these patterns remained distinct, with the SD-POb group showing higher food intake and caloric consumption than the HFD-POb group (food intake: +67.6%; caloric consumption: +33.1%). Additionally, significant differences were found in glycemic, insulinemic, and lipid profiles among the groups, notably for elevated fasting serum insulin levels in the SD-POb group compared to the SD-ROb (+141%) and HFD-POb (+151.3%) groups. Regarding physical performance, significant variations in maximal oxygen consumption were observed among the groups. The results show that the SD-ROb group exhibited an increase in VO2max compared to the SD-POb (+51.8%) and HFD-ROb (+10.30%) groups. However, no significant differences were detected in speed and distance traveled among the groups. The cross-sectional area of the gastrocnemius and soleus muscles was similar among the groups. Conclusion: ROb and POb conditions, regardless of the experimental diet, do not present differences related to energy metabolism. SD animals exhibit a specific improvement in VO2max compared to POb. HFD exposure time promotes a reduction in VO2max in the ROb condition. However, it is clear that the preferentially utilized energy substrate in HFD is fat, while in SD it is carbohydrates. Another important finding is related to the absence of histomorphological changes in muscle tissue under these conditions.
Keywords: Obesity-resistant; Obesity-prone; Metabolic assessment; Physical performance; Rats.
