Fructose 2,6-bisphosphate: changes during neonatal maturation and aging of rat and potential role in regulation of...

During the 6 days following birth, tissue levels of fructose-2,6-P2 in rat brain, liver, muscle, heart and kidney did not significantly change. However, by the tenth day postpartum fructose-2,6-P2 levels in brain, heart, and skeletal muscle increased approximately 50% and attained adult values. During maturation of liver, adult levels of fructose-2,6-P2 were not achieved until 3-4 weeks after birth or approximately at the time of maximum rates of gluconeogenesis. Renal fructose-2,6-P2 levels in the neonate were initially elevated and 2-3 weeks after birth decreased approximately 2.5-fold to adult values. With the exception of the pons-medulla, which showed no significant changes in fructose-2,6-P2 amounts, levels of this regulatory sugar from aging brain regions were generally decreased. The fructose-2,6-P2 levels from heart atria of old rats (24-30 month) were also significantly decreased. In diaphragm, the fructose-2,6-P2 levels were increased at 12 months of age and at 27 months of age were twice the level at 3 months. The fructose-2,6-P2 levels during the aging of liver, skeletal muscle (EDL and soleus), spleen, thymus, kidney, testis and lung were not significantly altered.