Immunocytochemical localization of heme oxygenase-2 in the rat cerebellum

Carbon monoxide (CO) is a gas that can permeate biological membranes and it has been suggested that the gas plays a signaling role in the brain by activating soluble guanylyl cyclase (sGC). CO is generated by heme oxygenase during the conversion of heme to biliverdin. In this study, we raised an antiserum against the chemically synthesized amino-terminal fragment of heme oxygenase-2 (HO-2) and studied the distribution of this enzyme in the rat cerebellum by an immunocytochemical method. Immunoreactivity specific for HO-2 was observed only in neurons. In the Purkinje cells and the basket cells of the cerebellum, immunoreactivity was detected in the dendrites and the somata but not in the axon terminals, suggesting that CO might be liberated primarily from the dendrites and somata rather than from the axons in this region of the rat brain.