Effect of scopolamine on the reactivity of the albino rat to footshock.

To determine if anticholergic drugs altered reactions to footshock, 9 female albino rats were tested for escape latencies following unsignaled presentations of footshock in a two-chambered shuttlebox. Different intensities of footshock (0, 0.04, 0.07, and 0.10 ma) were varied orthogonally with various doses of intraperitoneally injected scopolamine hydrobromide (0, 1.0, 4.0 and 16.0 mg/kg). Shock trials were randomly alternated with nonshock (pseudoshock) trials to estimate any drug-induced activity increase which might occur independently of any alteration in reactivity to aversive stimulation. Results indicated that scopolamine produced a significant increase in reactivity to footshock (i.e., shorter escape latencies) at near-threshold intensities as well as producing the expected increase in general activity.