ONTOGENY OF HEME OXYGENASE ACTIVITY IN THE HIPPOCAMPUS, FRONTAL CEREBRAL-CORTEX, AND CEREBELLUM OF THE GUINEA-PIG

Heme oxygenase (HO) catalyzes the oxidation of heme to produce carbon monoxide (GO), biliverdin and iron. CO is considered to function as a novel neuronal messenger in the brain analogous to nitric oxide. The o ntogeny of microsomal HO activity in the hippocampus, frontal cerebral cortex, and cerebellum of the immature fetal, mature fetal and adult guinea pig was determined using an optimized assay which quantitated h eme-derived CO formation by a gas chromatographic method. There was a distinct developmental profile of HO activity that was similar for all three brain regions. In particular, HO activity was maximal in the ma ture fetus compared with the immature fetus and the adult. These data demonstrate that HO activity is developmentally regulated and that the re is similar ontogeny of HO activity in the hippocampus, frontal cere bral cortex, and cerebellum of the guinea pig.