Hyperbaric oxygen treatment decrease's post-ischemic neurotrophin-3 mRNA downregulation in the rat hippocampus

The therapeutic effect of hyperbaric oxygen (HBO) on ischemic injury was in vestigated using in situ hybridization to detect the mRNA expression of neu rotrophin-3 (NT-3), which is thought to play a crucial role in protecting a gainst neuronal death induced by brain ischemia. The rats under investigati on were subjected to 10 min transient forebrain ischemia, and subsequently exposed to HBO (100% oxygen, 2.5 atm absolute) for 2 h. Levels of NT-3 mRNA in the CA1, CA2 and CA3 regions, and the dentate gyrus of the hippocampus were measured after various reperfusion periods. Neuronal death in the hipp ocampal CAI region was also measured. by Nissl staining, seven days post is chemia. The results demonstrated that HBO treatment significantly reduced t he ischemia-induced down-regulation of the NT-3 mRNA level at 4 h post isch emia, and significantly increased cell survival 7 days after reperfusion. T he findings suggest that an HBO treatment maintaining the NT-3 mRNA level i n the hippocampus can be beneficial to the ischemic brain within a certain time frame. (C) 2001 Lippincott Williams & Wilkins.