Footshock-induced sensitization of the acoustic startle response in two strains of mice.

It has been shown before that unconditioned footshocks can augment the acoustic startle response in rats. In the present study, male mice of two strains, C57Bl/6N and BALB/c, were compared with regard to footshock-induced sensitization of the acoustic startle response. Presentation of footshocks did not affect the acoustic startle response in C57Bl/6N mice, while in contrast, footshock-induced sensitization was apparent in the BALB/c strain. Shocked C57Bl/6N mice, but not BALB/c mice, displayed robust conditioning to the startle context when re-tested the next day. These findings indicate that mice may exhibit footshock-induced sensitization of the acoustic startle response, but that the effects of footshocks on the acoustic startle are strain- and time-dependent.