EFFECTS OF FRUCTOSE-1,6-BISPHOSPHATE ON BRAIN POLYAMINE BIOSYNTHESIS IN A MODEL OF TRANSIENT CEREBRAL-ISCHEMIA

We evaluated the effects on cerebral ischemia of a treatment with fruc tose-1,6-bisphosphate, a compound known to possess protective effects on acute ischemic injury in a variety of different tissues. We investi gated the ability of the compound, administered either 15 minutes befo re or 15 minutes after the ischemic insult, in reducing the ischemia-i nduced changes in polyamine brain levels. The experiments were perform ed in adult, chloral hydrate-anesthetized Mongolian gerbils that under went a 15 minutes ligation of the common carotid arteries followed by recirculation. Animals were sacrificed 1, 8 and 24 hours and immediate ly after the release of the occlusion. Polyamine brain levels were not modified during ischemia. Putrescine began to increase after eight ho urs from the release of the occlusion and we found it significantly in creased after 24 hours in the hippocampus and striatum. We did not det ect any significant changes in spermidine brain levels either during i schemia or during recirculation. Conversely, spermine appeared to decr ease in the hippocampus while it did not show changes in striatum and medulla-pons. The activity of ornithine decarboxylase, a key enzyme in the biosynthesis of polyamines, resulted enhanced at the end of the i schemic period in all the brain regions tested and showed a peak at ei ght hours of recirculation in striatum and hippocampus whereas returne d to control values in the medulla-pons. Fructose-1,6-bisphosphate sig nificantly reduced the ischemia induced changes in polyamine brain con tent when administered before the ischemic insult while did not show p rotective properties when administered post-ischemically.