[Effect of hypoxic-ischemic preconditioning of neonatal rats--morphometric evaluation of cerebral hemispheres]

Though the mechanisms of hypoxic-ischemic preconditioning are under investigation, it is considered that nitric oxide can play a critical role in the formation of this phenomenon. Experiments on white rats for study of cerebral hemisphere masses were carried out on 22-nd day after 3-hours hypoxic-ischemic exposure: (a) on 7-day-old rats, (b) on 7-day-old rats but 30 minutes before this exposure animals 3-times underwent short lasting (5 minutes) hypoxic-ischemic impacts (preconditioning), (c) same as previous experimental condition, but 15 minutes before beginning of preconditioning, animals were intraperitoneally injected either by non selective nitric oxide synthase (NOS) inhibitor (L-NAME) or (d) inducible NO synthase (iNOS) selective inhibitor--aminoguanidine. Received results showed that 3-times preconditioning efficiently protect brain from three hours hypoxic-ischemic exposure. It is evident that nitric oxide play a critical role in this protection--it completely eliminated morphological manifestation of hypoxic-ischemic preconditioning while aminoguanidine--just partially decreased the volume of brain hypoxic-ischemic ischemic damage.