Transcriptomic responses of the liver and adipose tissues to altered carbohydrate-fat ratio in diet: an isoenergetic study in young rats.

BACKGROUND

To elucidate the effects of altered dietary carbohydrate and fat balance on liver and adipose tissue transcriptomes, 3-week-old rats were fed three kinds of diets: low-, moderate-, and high-fat diets (L, M, and H) containing a different ratio of carbohydrate-fat (C-F) (65:15, 60:20, and 35:45 in energy percent, respectively).

METHODS

The rats consumed the diets for 9 weeks and were subjected to biochemical and DNA microarray analyses.

RESULTS

The rats in the H-group exhibited lower serum triacylglycerol (TG) levels but higher liver TG and cholesterol content than rats in the L-group. The analysis of differentially expressed genes (DEGs) between each group (L vs M, M vs H, and L vs H) in the liver revealed about 35% of L vs H DEGs that were regulated in the same way as M vs H DEGs, and most of the others were L- vs H-specific. Gene ontology analysis of these L vs H DEGs indicated that those related to fatty acid synthesis and circadian rhythm were enriched. Interestingly, about 30% of L vs M DEGs were regulated in a reverse way compared with L vs H and M vs H DEGs. These reversed liver DEGs included M-up/H-down genes ( for gluconeogenesis from amino acids) and M-down/H-up genes ( for gluconeogenesis from glycerol, for TG synthesis, and for beta-oxidation). We also analyzed L vs H DEGs in white (WAT) and brown (BAT) adipose tissues and found that both oxidation and synthesis of fatty acids were inhibited in these tissues.

CONCLUSIONS

These results indicate that the alteration of dietary C-F balance differentially affects the transcriptomes of metabolizing and energy-storing tissues.