Both high-intensity interval training and low-intensity endurance training decrease intrahepatic lipid deposits via alterations of the expression of HIF-1, HIG2 in a murine model of NAFLD

Abstract

Background and aims. — Non-alcoholic fatty liver disease (NAFLD) is known as a serious disease associated with malnutrition and overweight habits. The aim of this study was to investigate the effect of the eight-week high-intensity interval training (HIIT) and the low-intensity endurance training (ET) on the expression of HIF-1, HIG2 and intrahepatic lipid content (IHL) in the rats suffering from non-alcoholic fatty liver disease (NAFLD). Methods. — To this aim, forty Wistar rats were selected randomly and divided into four groups: NAFLD, NAFLD + HIIT (N + HIIT), NAFLD + ET (N + ET), and control groups. The protocol of the N + HIIT group consisted of high-intensity running separated with light running; the protocol of the N + ET group was matched with the whole ran distance of the N + HIIT group with a lower intensity. After eight weeks, a portion of the liver of each rat was excised and frozen in liquid nitrogen for assessment of HIF-1, HIG2 mRNA levels, and IHL. Results. — The results showed that there was a significant difference between the groups in terms of the expression of HIF-1 (X2 = 16.42, P = 0.001), HIG2 (X2 = 12.43, P = 0.006) and IHL content (X2 = 32.84, P = 0.001). Moreover, HIF-1 and HIG2 mRNA levels were found to be decreased in N + HIIT vs. NAFLD (P = 0.024 and P = 0.031) and N + ET vs. NAFLD (P = 0.012 and P = 0.012), respectively. There was no significant difference in the expression of HIF-1 and HIG2 between N + HIIT and N + ET groups (P = 0.895 and P = 0.453). There were also significant differences in terms of IHL between NAFLD and N + HIIT groups (P = 0.001), and between NAFLD and N + ET groups (P = 0.001). A significant difference was also observed in the IHL content between N + HIIT and N + ET groups (P = 0.003). Conclusion. — Overall, it could be concluded that both N + HIIT and N + ET protocols reduced the content of liver fat, thereby decreasing fatty liver disease by reducing the expression of HIF-1 and HIG2 genes. It seems that the decrease of hypoxia and lipid droplet-associated with proteins in hepatocytes could lead to the improvement of fatty liver disease. Published by Elsevier Masson SAS.