Effect of High‐Fat Diet on Body Composition and Autonomic Modulation in Rats
Authors: de Souza Campiello Talarico Ana Laura , Simões Barbara Bim , Rozza Caroline Altenburg , Brognara-Dias Fernanda , Dias Daniel Penteado Martins 
Published: April 2020

Currently, more than a third of the world’s population is overweight or obese. In addition, obesity increases the risk of myocardial infarction, heart failure and ventricular remodeling, directly affecting the cardiocirculatory system. The consumption of different types of fats may favor the onset of these cardiovascular diseases. Thus, the present study compared the effects of high‐fat diets with different compositions (predominance of saturated or unsaturated fats) on body composition and cardiovascular parameters of rats. Wistar male rats were assigned into groups and fed with control (standard rat chow), saturated high‐fat diet [standard rat chow enriched with grated raw coconut (1:1)] or unsaturated high‐fat diet [standard rat chow enriched with crushed roasted almonds (1:1)] during eight weeks. The body weight was evaluated twice a week during the whole feeding phase. At the end of this phase, all rats were anesthetized with a ketamine/xylazine mixture and implanted with an electrode for electrocardiogram (ECG) recording and a catheter into the femoral vein for drugs administration. Two days later, unanesthetized animals had the ECG recorded during 30 minutes at baseline, followed by atropine (1 mg/kg, i.v) and propranolol (2 mg/kg, i.v) administration, separated by a 15 minutes interval. On the next day, rats were subjected to the same protocol, but autonomic blockers were given in opposite order. Right after ECG data sampling ceased, animals were fully anesthetized and had the left lobe of the liver, epididymal and retroperitoneal adipose tissues (on both sides) collected and weighed. Despite the difference in diet composition, animals showed comparable weight gain in all groups over time. No difference was observed on the liver weight among groups. However, animals fed with unsaturated enriched diet showed a strong trend towards an increase in the weight of retroperitoneal adipose tissue (control diet: 6.7 ± 1 g; saturated diet: 7.7 ± 1 g; unsaturated diet: 12.9 ± 3 g). Also, both groups receiving high‐fat diets showed a trend towards augmented epididymal adipose tissue weight (saturated diet: 8.2 ± 1 g; unsaturated diet: 10.9 ± 3 g), as compared to control group (control diet: 5.8 ± 1 g). Concerning the autonomic modulation, baseline heart rate and the intrinsic heart rate were comparable among groups studied. Nevertheless, a trend towards reduced vagal tone was seen in unsaturated diet group (control diet: Δ114 ± 24 bpm; saturated diet: Δ121 ± 20 bpm; unsaturated diet: Δ86 ± 11 bpm). In conclusion, although the composition of the diet did not influence the weight gain of the rats over the eight weeks, the current data indicate that the body composition, especially adipose tissue weight, may differ depending on diet basis. In addition, the unsaturated diet seems to decrease vagal tone in rats.

Support or Funding Information

Barao de Maua University Center: 347/19; FAPESP: 2017/05163‐6