Inducible protective processes in animal systems: VIII. Enhancement of adaptive response by nicotinamide

The molecular mechanism of the adaptive response or inducible DNA repair pr ocess has not been clearly demonstrated in eukaryotic systems. The involvem ent of poly(ADP-ribose) polymerase (PARP), a DNA repair enzyme has been rep orted in the adaptive response (Shadley and Wolff, 1987; Wiencke, 1987), He nce, the present studies were undertaken to understand the role of PARP in ethyl methanesulfonate (EMS)-induced adaptive response in mouse bone marrow cells by employing the inhibitor of this enzyme, nicotinamide. Inter-, pre - and post-treatments of nicotinamide with EMS were made. The results have revealed that there is a reduction in the frequencies of chromosomal aberra tions compared with combined or challenge treatment at the different recove ry times tested. These results are discussed with reference to the enhancem ent of the adaptive response by nicotinamide in mouse bone marrow cells.