The Effects of Dietary Interventions on mRNA Expression of Peroxisome Proliferator Activated Receptor Isoforms (PPAR Isoforms)in Rat Skeletal Muscle

ABSTRACT

We determined the effects of dietary manipulations on messenger RNA of peroxisome proliferators activated receptor isoforms (i.e., PPAR alpha, beta/delta, gamma)in red vastus lateralis muscle of rats. Total 16 male Sprague-Dawley rats were used, and animals were divided into one of two dietary conditions :either chow diet group (CHOW ;n =8 )in which animals were fed with standard rodent chow (61.8% carbohydrate, 15.7% fat, 22.5% protein )or high fat diet group (FAT n =8 ) in which animals were fed 24.3% carbohydrate, 52.8% fat, 22.9% protein. At the end of the 8 weeks of experimental pe-riod, red vastus lateralis muscle was dissected out from all animals, and PPAR alpha, beta/delta, gamma mRNA expression was deter-mined. There was no significant difference in body mass (BM )between CHOW and FAT. As expected, blood glucose and free fatty acid (FFA )concentration was higher in FAT than CHOW (p <0.05 ), and lactate concentration was significan-tly lower in FAT compared to CHOW (p <0.05 ). Insulin concentration tended to higher in FAT than CHOW (67.2 +/- 21.9 vs. 27.0 +/-5.2 pmol/L ), but it did not reach to the statistical significance. Gene expression of PPAR alpha was not signifi-cantly different between CHOW and FAT. It was not also significantly different in PPAR beta/delta. Interestingly, expression of mRNA in PPAR gamma however, was markedly depressed in FAT compared to CHOW (approximately 3 fold higher in CHOW ; p <0.05 ). Results obtained from present study implies that PPAR gamma (as compensatory function of PPAR alpha is expressed ) possibly exerts another major tuning roles in fatty acid transport, utilization, as well as biosynthesis in skeletal muscle cells. The situations and conditions that can be postulated for this implication need to be further examined.