Hydrogen peroxide-induced thymidine incorporation into cultured rat astrocytes

Abstract

We characterized [methyl-3H]thymidine ([3H]thymidine) and [5-3H]uridine ([3H]uridine) incorporation into cultured astrocytes and neurons in the presence and absence of hydrogen peroxide (H2O2) in order to define the response to oxidative stress in the central nervous system. [3H]Thymidine incorporation into cultured astrocytes was remarkably decreased by N6,2′-O- dibutyryladenosine 3′,5′-cyclic monophosphate (DBcAMP), a permeable analogue of cAMP, which induced a morphological change from the polygonal form (undifferentiated astrocytes) to the process-bearing one (differentiated astrocytes). H2O2 induced [3H]thymidine, but not [3H]uridine, incorporation into cultured astrocytes at only an early time from 24 h after DBcAMP treatment, although the absolute quantities of [3H]thymidine incorporation into astrocytes pretreated with DBcAMP were less than those into astrocytes pretreated without DBcAMP. Hydroxyurea, a replicative DNA synthesis inhibitor, suppressed dose-dependently and completely [3H]thymidine incorporation into astrocytes pretreated without DBcAMP, but not astrocytes pretreated with DBcAMP. H2O2 did not stimulate [3H]thymidine or [3H]uridine incorporation into astrocytes pretreated without DBcAMP and neurons. These findings indicate that only astrocytes pretreated with DBcAMP are able to increase thymidine incorporation specifically in the presence of H 2O2 for a purpose other than proliferation, including the repair of H2O2-induced DNA injury, for example. ©2006 The Japanese Pharmacological Society.