The absence of impairment of cliff avoidance reaction induced by subchronic methamphetamine treatment in inbred strains of mice.

Cliff avoidance reaction (CAR), an index of behavioral teratology in rodents, can be impaired by motor, arousal, or cognitive dysfunction. We formerly reported subchronic administration of methamphetamine (MAP) induced the CAR impairment, which might reflect MAP-induced cognitive dysfunction, in three strains of rats. In this study, the effects of subchronic MAP treatment on the behavioral sensitization in stereotypy (stereotypy sensitization) and CAR were examined in two inbred strains of male mice; C57BL/6J(C57) and DBA/2J(DBA). The animals received 4 mg/kg/day MAP intraperitoneally for 28 days. There were apparent strain differences in the development of stereotypy sensitization induced by chronic MAP; DBA mice developed stereotypy sensitization quickly, but C57 did not. Unlike rats, neither strains of mice showed the CAR impairment. These results suggest that chronic MAP (4 mg/kg) administration did not introduce any cognitive dysfunction measured by CAR in the two inbred mice, DBA and C57. The discrepancy between rats and mice is still unclear. It might relate to the species-selective effect of MAP on the CAR impairment. Further studies should to be required.