Heme oxygenase1 (HSP-32) is induced in myelin-phagocytosing Schwann cells of injured sciatic nerves in the rat

Schwann cells participate in myelin phagocytosis in the early stage of Wall erian degeneration, prior to the recruitment of macrophages. This is the fi rst report that Schwann cells induce heme oxygenase-1 (HO-1), a 32-kDa heat shock protein, only when they have transformed into myelin-phagocytosing c ells from myelinating cells (days 2-3) immediately after crush injury of ra t sciatic nerves. Double immunofluorescent labelling for HO-1 and transferr in receptors revealed that HO-1-immunoreactive Schwann cells also expressed transferrin receptors suggesting activation of iron metabolism. The transi ent induction of HO-1 in Schwann cells may contribute to the adaptive funct ion in an altered environment when the cells have lost contact with axons, and may play a crucial role in the ensuing regeneration.