Objective: The aim of this study was to investigate the effect of high intensity interval training and flax seed oil supplementation on liver and intestine ABCA1, SR-BI, ABCG1, LXR gene expression, as well as the concentration of HDL, LCAT and plasma lipids in male rats.

Methods: Forty adult Wistar rats were randomly divided into eight groups (n=5) including control-saline, training-saline, control-flaxseed oil (With 3 doses), and training-flaxseed oil. The training groups were given high-intensity interval training (10 weeks, five sessions in week) on a rodent treadmill at 90–95% of VO₂max and supplement groups also received flaxseed oil with three different doses (10, 20 and 30 mg/kg per cage). Then rats were sacrificed and samples were collected.

Results: The results showed that the training created a significant increase (P<0.01) in the expression of liver ABCA1 and ABCG1genes, intestine ABCA1, LXR and SRBI genes, as well as the plasma HDL and LCAT concentration. Supplements caused a significant decrease (P<0.001) in expression of liver ABCA1 genes. There was a significant and positive correlation between liver ABCG1 gene expression with plasma HDL and LCAT, as well as between intestine LXR gene expression with plasma HDL.

Conclusion: Long-term consumption of even unsaturated oils may have adverse effects on the cardiovascular system, but high intensity interval training can bring health benefits by increasing the expression of genes involved in reverse cholesterol transport.