As shown in a previous study from our group, AET was efficient in producing cardiovascular changes in OZR, such as a reduction in heart rate due to vagal hypertonia in the trained groups .
The OZR + TR group had a lower body fat content than the OZR group, as also shown by Disanzo and You who found that obesity led to an increase in endothelial growth factor A (VEGF-A) that is responsible for stimulating angiogenesis in adipose tissue counteracting glycolytic metabolism in this tissue and contributing to their decrease by exercise .
Here, we showed that LV intramuscular fat was higher in the OZR group compared with LZR, LZR + TR, and OZR + TR.
In the present study, obesity decreased the cardiac microRNA-29c expression in OZR by 47% compared with LZR, which induced an increase in the cardiac CVF.
In our previous study, although there was no statistical difference (p = 0.07), a 25% reduced time E/A wave ratio was found when OZR was compared with untrained LZR , suggesting damage in the contractile myocardium.
The NCX1 protein, which is the direct target of microRNA-1, was downregulated in OZR compared with the other groups (LZR, LZR + TR, and OZR + TR); this data indicates a possible antagonism between NCX1 and microRNA-1 expressions .
In the present study, there was an increase in the RYR2 receptor expression in both trained groups (LZR + TR and OZR + TR) compared with their controls (LZR and OZR).
We also observed that SERCA-2a expression was decreased in LZR + TR compared with LZR and a tendency in OZR+ TR compared with OZR. While SERCA-2a expression decreased, the RYR2 expression was increased that could be causing an imbalance in the sarcoplasmic [Ca.sup.2+] content.
In conclusion, obesity downregulated microRNA-29c in OZR possibly leading to increased cardiac collagen content.
Content of retroperitoneal (b) and epidydimal fat (c) in LZR (control lean group), LZR + TR (trained lean group), OZR (control obese group), and OZR + TR (trained obese group).
Cardiac intramuscular fat contents (c) were evaluated by histological analysis in LZR (lean group control), LZR + TR (lean trained group), OZR (obese group control), and OZR + TR (obese trained group).
* p < 0.05 versus LZR and # p <0.03 versus LZR, LZR + TR, and OZR + TR.