Fructose-1,6-Bisphospate does not preserve ATP in hypoxic-ischemic neonatal cerebrocortical slices

• Published in: Brain research Vol. 1238; pp. 230 - 238
• Main Authors: Liu, Jia, Hirai, Kiyoshi, Litt, Lawrence
• Format: Journal Article
• Language: English
• Published: 12.08.2008
• ISSN: 0006-8993
• DOI: 10.1016/j.brainres.2008.08.005

Fructose-1,6-bisphosphate (FBP), an endogenous intracellular metabolite in glycolysis, was found in many preclinical studies to be neuroprotective during hypoxia-ischemia (HI) when administered exogenously. We looked for HI neuroprotection from FBP in a neonatal rat brain slice model, using 14.1 Tesla 1 H / 31 P/ 13 C NMR spectroscopy of perchloric acid slice extracts to ask: 1) if FBP preserves high energy phosphates during HI; and 2) if exogenous [1- 13 C]FBP enters cells and is glycolytically metabolized to [3- 13 C]lactate. We also asked: 3) if substantial superoxide production occurs during and after HI, thinking such might be treatable by exogenous FBP's antioxidant effects. Superfused P7 rat cerebrocortical slices (350μm) were treated with 2 mM FBP before and during 30 min of HI, and then given four hours of recovery with an FBP-free oxygenated superfusate. Slices were removed before HI, at the end of HI, and at 1 and 4 hours after HI. FBP did not improve high energy phosphate levels or change 1 H metabolite profiles. Large increases in [3- 13 C]lactate were seen with 13 C NMR, but the lactate fractional enrichment was always (1.1±0.5)%, implying that all of lactate's 13 C was natural abundance 13 C, that none was from metabolism of 13 C-FBP. FBP had no effect on the fluorescence of ethidium produced from superoxide oxidation of hydroethidine. Compared to control slices, ethidium fluorescence was 25% higher during HI and 50% higher at the end of recovery. Exogenous FBP did not provide protection or enter glycolysis. Its use as an antioxidant might be worth studying at higher FBP concentrations.