Effect of aging and oxidative/genotoxic stress on poly(ADP-ribose) polymerase-1 activity in rat brain.

Poly(ADP-ribose) polymerase-1 (PARP-1, EC 2.4.2.30), a DNA-bound enzyme, plays a key role in genome stability, but after overactivation can also be responsible for cell death. The aim of the present study was to investigate PARP-1 activity in the hippocampus, brain cortex, striatum and cerebellum in adult (4 months) and aged (24 months) specific pathogen free Wistar rats and to correlate it with PARP-1 protein level and p53 expression. Moreover, the response of PARP-1 in adult and aged hippocampus to oxidative/genotoxic stress was evaluated. Our data indicated a statistically significant enhancement of PARP-1 activity in aged hippocampus and cerebral cortex comparing to adults without statistically significant changes in PARP-1 protein level. The expression of p53 mRNA was elevated in all aged brain parts with the exception of the cerebral cortex. Our data suggest that enhancement of PARP-1 activity and p53 expression in aged brain may indicate higher DNA damage. Our data also indicate that during excessive oxidative/genotoxic stress there is no response of PARP-1 activity in aged hippocampus in contrast to a significant enhancement of PARP-1 activity in adults which may have important consequences for the physiology and pathology of the brain.