Abstract: AIM:To observe the neuroprotection effects exogenous adrenomedullin (AM) against hypoxic- ischemia/reperfusion damage (HIRBD) in neonatal rat models. METHODS:Forty neonatal rats were randomly divided into Control Group (n =8, with sham operation), Hypoxic-ischemia/reperfusion (HIR) Group and Intervention Group (n =8, wth intraperitoneal AM injection 0, 6 and 12 h after making model). All rats were decapitated at 48 hours after reperfusion, and the cerebral slices were made at the 2 mm level in front of the interaural line. The pathobiological changes of brain tissue were observed by the method of HE dye in light microscope, and the levels of nitrogen monoxide synthase (NOS), glutathion (GSH) and myeloperoxidase (MPO) in neonatal rats cerebral tissue were determined by using chromatometry. RESULTS:Hypoxic-ischemia/reperfusion could induce obviously cerebral pathological change which could be improved by AM. The brain tissue levels of cNOS and GSH in AM 0 and 6 h Group were significantly higher than those of HIR Group (P <0. 05). The brain tissue levels of iNOS and MPO in AM 0, 6 h Group were significantly lower than those of HIR Group (P <0. 05). CONCLUSION:The exogenous AM given 0-6 h after hypoxic-ischemia may protect the neonatal rats from HIRBD by enhancing GSH activities and the release of NO, checking the infiltration of neutrophile granulocyte into cerebral tissues.

Key words: hypoxia-ischemia, brain, adrenomedulin, nitricoxide synthase, glutathione, peroxydase, rat