FRUCTOSE 2,6-BISPHOSPHATE - CHANGES DURING NEONATAL MATURATION AND AGING OF RAT AND POTENTIAL ROLE IN REGULATION OF GLUCOSE-UTILIZATION

During the 6 days following birth, tissue levels of fructose-2,6-P2 in rat brain, liver, muscle, heart and kidney did not significantly chan ge. However, by the tenth day postpartum fructose-2,6-P2 levels in bra in, heart, and skeletal muscle increased approximately 50% and attaine d adult values. During maturation of liver, adult levels of fructose-2 ,6-P2 were not achieved until 3-4 weeks after birth or approximately a t the time of maximum rates of gluconeogenesis. Renal fructose-2,6-P2 levels in the neonate were initially elevated and 2-3 weeks after birt h 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 regio ns were generally decreased. The fructose-2,6-P2 levels from heart atr ia of old rats (24-30 month) were also significantly decreased. In dia phragm, 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 sol eus), spleen, thymus, kidney, testis and lung were not significantly a ltered.