It has been shown before that unconditioned footshocks can augment the acou
stic startle response in rats. In the present study, male mice of two strai
ns, C57BI/6N and BALB/c, were compared with regard to footshock-induced sen
sitization of the acoustic startle response. Presentation of footshocks did
not affect the acoustic startle response in C57BI/6N mice, while in contra
st, footshock-induced sensitization was apparent in the BALB/c strain. Shoc
ked C57B1/6N mice, but not BALB/c mice, displayed robust conditioning to th
e startle context when re-tested the next day. These findings indicate that
mice may exhibit footshock-induced sensitization of the acoustic startle r
esponse, but that the effects of footshocks on the acoustic startle are str
ain- and time-dependent. (C) 2001 Elsevier Science B.V. All rights reserved
.