The nicotinamide nucleotide transhydrogenase gene could impair blood glucose level stability and increase basal metabolism

C57BL/6J (B6J) is the most widely used mouse strain for metabolic research. It carries a spontaneous mutation in the nicotinamide nucleotide transhydrogenase (Nnt) gene. This study compared blood glucose levels in B6J and Kunming (Km) mice as control. It was observed that blood glucose levels in B6J and Km mice at 4 weeks of age decreased post feeding and reached the lowest level at 24 hr of fasting. Blood glucose was significantly higher in B6J mice than that in Km mice at 0 hr, 2 hr and 10 hr of fasting. In addition, the correlation between the Nnt gene, growth traits and the feed conversion efficiency ratio (FCR) in (B6J × Km) F2 generation (N = 342) was also analyzed. We found that Nnt was significantly associated with body weight at 3 weeks (IBW) (P＜0.01) and 5 weeks (FBW) (P＜0.05) and average metabolic body weight (AMBW) (P＜ 0.01) but was not associated with average daily feed intake (AFI), average daily gain (ADG) and FCR. Furthermore, qRT-PCR revealed that the expression levels of Glut-1, Glut-2, Akt-1, Irs-1 and Ucp-2 genes were significantly different in high and low-FCR mice. Our study offers novel evidence of the roles of Nnt gene in metabolism and growth.