Neuroprotective role of heme-oxygenase 1 against iodoacetate-induced toxicity in rat cerebellar granule neurons: Role of bilirubin.

Heme oxygenase (HO) catalyses the breakdown of heme to iron, carbon monoxide and biliverdin, the latter being further reduced to bilirubin. A protective role of the inducible isoform, HO-1, has been described in pathological conditions associated with the production of reactive oxygen species (ROS). The aim of this study was to investigate the role of HO-1 in the neurotoxicity induced by iodoacetate (IAA) in primary cultures of cerebellar granule neurons (CGNs). IAA, an inhibitor of the glycolysis pathway, reduces cell survival, increases ROS production and enhances HO-1 expression in CGNs. Furthermore, the induction of HO-1 expression by cobalt protoporphyrin (CoPP) prevented cell death and ROS production induced by IAA, whereas the inhibition of HO activity with tin mesoporphyrin exacerbated the IAA-induced neurotoxicity. The protective effect elicited by CoPP was reproduced by bilirubin addition, suggesting that this molecule may be involved in the protective effect of HO-1 induction in this experimental model.