Approximately 30% of extremely premature infants survive with central nervous system (CNS) damage. We have shown that fructose-1 ,6-bisphosphate (FBP) dramatically reduces CNS injury following reversible (adult rats) and permanent carotid artery occlusion + hypoxia (Levine model - neonatal rats). Furthermore, we demonstrated marked reduction in hypoxia-induced injury to cultured astrocytes. We also demonstrated that 3.5 mM FBP decreased Ca2+ uptake by hypoxic astrocytes (95% N2/5% Co2) in vitro and that FBP reduced extracellular glutamate concentrations of brain.In vivo, FBP markedly reduced the serum [Ca2+] of 7 day old rats while significantly reducing CNS injury. We hypothesize that FBP protects the CNS by preventing or reducing influx or release of calcium caused by hypoxic-ischemic stress. To test this hypothesis, we will: 1) Determine if FBP prevents or reduces hypoxia-induced changes in intracellular free Ca2+ in neurons, astrocytes and mixed cultures of neurons arid astrocytes. We also will determine if other phosphorus containing compounds of glycolysis reduce intracellular free [Ca2+]. 2) Determine if FBP alters glutamate induced increases in free intracellular Ca2+ and if FBP protects by effects on NMDA and AMPA receptors. Studies will be done to determine if FBP reduces hypoxia-induced release of glutamate from neurons. Evidence of cell injury will be sought by LDH content, Trypan blue uptake, TUNEL Staining, and DNA laddering. 3) Determine if FBP decreases regional Ca2+ uptake by the brains of 7 day old rats (Levine model) (autoradiography) and if it reduces local brain glutamate concentrations (piglets) (microdialysis). These findings will be compared to those occurring with EDTA. 4) Determine if FBP-induced Changes in brain [Ca2+] are related to improved cerebral blood flow(CBF). Since decreased serum [Ca2+] may induce changes in cardiac output, CBF and cardiac output, (microspheres), cerebral oxygen consumption, and changes in redox state (aa3) will be determined in piglets and correlated with the serum [Ca2+]. 5) Determine if FBP reduces magnetic resonance imaging and magnetic resonance spectroscopy indices of CNS injury in piglets following global ischemia and correlate these changes with the serum [Ca2+]. Knowing the mechanisms of action of FBP may allow us to design drugs that prevent CNS injury without serious side effects.
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