24 h-fasting effects on the brown and white adipose tissue and liver

The functional balance between brown adipose tissue (BAT) and white adipose tissue (WAT) is important for metabolic homeostasis. We compared the effects of fasting on the gene expression profiles in BAT, WAT and liver, using DNA microarray analysis. Tissues were obtained from rats that had been fed or fasted for 24 h. Taking the false discovery rate (FDR) into account, we extracted the top 1,000 genes that were expressed differentially between fed and fasted rats. In all three tissues, Gene Ontology analysis revealed marked changes in the expression of metabolism category genes and a hypergeometric test demonstrated that within this category, lipid and protein biosynthesis-related genes were down-regulated. These findings indicate simultaneous down-regulation of genes involved in energy-consuming pathways in the BAT, WAT and liver of fasted rats. In the BAT of fasted rats, there was marked up-regulation of genes in the protein ubiquitination category, suggesting that the ubiquitin-proteasome system is involved in saving energy as an adaptation to food shortage.

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Nakai Y, Hashida H, Kadota K, Minami M, Shimizu K, Matsumoto I, Kato H, Abe K