Exposure of C57BL/6J mice to long photoperiod during early life stages increases body weight and alters plasma metabolomic profiles in adulthood.

Perinatal photoperiod is an important regulator of physiological phenotype in adulthood. In this study, we demonstrated that postnatal (0-4 weeks old) exposure of C57BL/6J mice to long photoperiod induced persistent increase in body weight until adulthood, compared with the mice maintained under short photoperiod. The expression of peroxisome proliferator-activated receptor δ, a gene involved in fatty acid metabolism, was decreased in 10-week-old mice exposed to long photoperiod during 0-4 or 4-8 weeks of age. Plasma metabolomic profiles of adult mice exposed to a long photoperiod during the postnatal period (0-4 LD) were compared to those in the mice exposed to short photoperiod during the same period. Cluster analysis revealed that both carbon metabolic pathway and nucleic acid pathway were altered by the postnatal photoperiod. Levels of metabolites involved in glycolysis were significantly upregulated in 0-4 LD, suggesting that the mice in 0-4 LD use the glycolytic pathway for energy expenditure rather than the fatty acid oxidation pathway. In addition, the mice in 0-4 LD exhibited high levels of purine metabolites, which have a role in neuroprotection. In conclusion, postnatal exposure of C57BL/6J mice to long photoperiod induces increase in body weight and various changes in plasma metabolic profiles during adulthood.