The Regulation Of DHEA And Training On The Lipolysis In Liver, Heart And Gastrocnemius Muscle In Male Rats Through PPAR α

Purpose: Peroxisome proliferator-activated receptor a(PPARa) is a member of the nuclear receptor superfamily and functions as a transcription factor.When it is activated by its ligand,it can induce the expression of some genes and these genes are associated with the metabolism of fatty acids. Considering the great lipolysis of endurance training,one of the purposes of this study was to determine the obligation of PPARa on this function; This study was also to observe the respective effects of endurance training and DHEA on PPARa gene expression.Method: Forty adult male Sprague-Dawley rats are divided into four groups at random: (A) control group, (B) DHEAS (DHEA sulfate) group, (C) training group, (D) DHEAS and training group. DHEAS was administrated by subcutaneous injection at a daily dose of 20mg/kg body weight in group B and D for six weeks. Animals in group C and group D received endurance training by running on the treadmill for 1 hour at a speed of 25m/min,6 days per week,for seven weeks. Result: 1. All the four groups had the same level of serum triglyceride and cholesterol. 2. Among the four groups there was no significant difference in mRNA profiles of PPARa and its target enzyme acyl-CoA oxidase (AOX) by RT-PCR in liver, heart and gastrocnemius muscle. 3. Western blot analysis of PPARa showed the following changes: (1) The level of PPARa protein was significantly higher in group C and D than in group A (p<0.01, respectively) in liver. (2) The above effect was more dramatic in heart (p<0.001, respectively). Besides, the level ofPPARa protein in group B was also higher than in group A (p<0.05). (3) Significant difference in PPARa protein expression was only observed between group D and group A (p<0.05) in gastrocnemius muscle.Conclusion : l.The results indicated that administration of exogenous DHEA and endurance training regulated the expression of PPARa gene in translation and post-translation level; 2. DHEA treatment only resulted in increased PPARa protein level in heart, while endurance training significantly induced PPARa gene expression not only in heart but also in liver and gastrocnemius muscle.