Inducible protective processes in animal systems: adaptive response to a low dose of methyl methanesulfonate in mouse bone marrow cells.

To investigate the induction of adaptive response (inducible protective processes) in mitotic cells of Swiss albino mouse, a monofunctional alkylating agent methyl methanesulfonate (MMS) was employed. When the animals treated with a low dose of 50 mg/kg body weight were challenged with a subsequent high (challenging) dose of 150 mg/kg body weight, after different time lags (2,5,8 or 10 hr), the yield of chromosomal aberrations in bone marrow cells was found to be significantly reduced compared to the additive effects of both conditioning and challenging doses. It seems, therefore, that the low dose of MMS employed has made the cells less sensitive against further clastogenic effect of challenge dose of MMS. The data clearly suggest that the phenomenon of adaptive response to methylating agents can be encountered in in vivo mammalian cells. Furthermore, it is also observed that ethylating agent EMS is a poor inducer of adaptive response than its corresponding methylating agent MMS in the bone marrow cells of mouse.