Effects of aerobic exercise on PPARα signaling in diabetes rats and its association with PPARγ

Abstract

To investigate the improved effects of 4-week aerobic exercise on blood glucose and lipid of diabetes mellitus (DM) rats and its association with peroxisome proliferators-activated receptor (PPAR)α signaling and PPARγ. Six-week old male SD rats were fed with 8-week high-fat diet following a single intraperitoneal injection of streptozotocin to establish DM models rats. Except control group rats (fed with ordinary diet), DM model rats were randomly divided into DM group, trained DM group (TDM), TDM plus PPARγ agonist pioglitazone group (TDP), and TDM plus PPARγ inhibitor GW9662 group (TDG), 8 rats in each group. TDM, TDP and TDG rats were undertaken a medium-intensity incremental treadmill training for 4 weeks, once a day and 6 days a week (1st week: 15 m/min speed lasting for 30 min; 2nd week: 15 m /min for 60 min; 3rd week: 20 m/min for 60 min; 4th week: 20 m/min for 90 min). All the rats were fed with ordinary diet during 4-week exercise. The rats were anesthetized and blood samples were collected at 36 h after the last exercise, and liver and gastrocnemius were collected after the rats were sacrificed. Fasting blood glucose and blood lipid were detected (blood glucose, insulin and TC, TG, HDL and LDL). The protein levels of PPARα, adenosine monophosphate (AMP)-activated protein kinase (AMPK) and carnitine palmitoyl transferase 1 (CPT1) in the liver and gastrocnemius of the rats were measured by Western blot. ①Compared with control rats, the serum levels of TC, TG, LDL, and FBG (＞11.1 mmol/L) in DM rats were significantly increased, indicated the successful establishment of DM rats. ②Compared with DM rats, accompanied with the improvements of fasting blood glucose and blood lipid, the protein levels of PPARα, AMPK and CPT1 were significantly increased in the liver and gastrocnemius of TDM rats. ③Compared with TDM rats, no significant changes were found in TDG rats including the protein levels of PPARα and CPT1 (liver and gastrocnemius) as well as AMPK (liver), except for a decrease of AMPK in gastrocnemius; while the protein levels of PPARα, AMPK and CPT1 were all increased in the liver and gastrocnemius of TDP rats. Aerobic exercise-induced improvements of blood glucose and blood lipid was related to the up-regulation of AMPK-PPARα-CPT1 signaling pathway in the liver and muscle of DM rats. The exercise-induced enhancement of PPARα in DM rats was unrelated to PPARγ, but PPARγ activation could further increase the protein levels of AMPK-PPARα-CPT1 in TDM rats.