Developmental delineation of metabolic-patterns of neonatal mice by using NMR-metabolic profiling on highly-diluted urine.

Blood circulation and the route of nutritional supply both change dramatically in the immediate neonatal period. These systemic shifts lead to adjustment of metabolic patterns in the neonate, with alterations in the spectrum of metabolites in body fluids. We have investigated whether (1)H-NMR-based metabolic profiling (NMR-MP) with principal component analysis (PCA) can be used to evaluate metabolite profiles in highly-diluted samples of individual neonatal mouse urine. We report that a 60-fold dilution of urine gave a reproducible NMR-MP analysis. Here the NMR spectral patterns and PCA score plot clearly delineated the developmental changes in urine metabolites in the immediate neonatal period. These results suggest that NMR-MP may offer a powerful method for assessing the physiology and toxicity of chemicals in neonatal periods of experimental animals.

Fasting induced up-regulation of activating transcription factor 5 in mouse liver.

AIMS: Food deprivation (fasting) is commonly encountered in the lives of animals and humans. In mammals, adaptive responses predominantly include the induction of hepatic gluconeogenesis, but the regulatory mechanisms remain unclear. Atf5 (activating transcription factor 5) is a transcription factor of the ATF/cAMP response element-binding protein family and is expressed abundantly in human liver. Atf5 has been associated with stress responses, cell differentiation, proliferation, and survival. However, its role in the liver response to in vivo food deprivation has not yet been investigated. MAIN METHODS: Adult mice were food-deprived for 48 h and the expression of two Atf5 mRNA subtypes (Atf5-R1 and Atf-R2) and gluconeogenic factors was investigated. Using in vitro cell culture, Pgc-1alpha (peroxisome proliferator-activated receptor-gamma coactivator-1alpha) promoter activities after ectopic expression of Atf5 and Cebpg (CCAAT/enhancer-binding protein gamma) proteins were measured. KEY FINDINGS: The Atf5-R1 transcript was found to be abundant in liver and other energy metabolism-related organs; Atf5-R2 was prominent in the testis. Fasting resulted in elevation of the expression of both Atf5-R1 and R2 in the liver. Interestingly, up-regulation of Atf5 was accompanied by increased expression of Cebpg and Pgc-1alpha. In human hepatoma cells (HepG2), but not in human cervical carcinoma cells (HeLa), forced expression of Atf5 and Cebpg cooperatively stimulated Pgc-1alpha promoter activity, suggesting that hepatic Pgc-1alpha could be induced by Atf5 and Cebpg in cooperation with other hepatic factors. SIGNIFICANCE: Hepatic Atf5 might be potentially involved in the induction of gluconeogenetic factors during in vivo fasting stress.