The long-term effects of diazepam, lorazepam, and buspirone on behavioral suppression by a shock signal

1. Two experiments examined the long-term effects of treatment with buspirone (a nonbenzodiazepine anxiolytic), diazepam, or Lorazepam (two pharmacokinetically distinct benzodiazepines) on the capacity of a shock cue to disrupt appetitively conditioned behavior. 2. In Experiment 1, rats were injected with diazepam (5 mg/kg), buspirone (1.5 mg/kg or .75 mg/kg), or saline shortly before each of 12 bar press training sessions. Injections were suspended and three days later the rats received five days of Pavlovian fear conditioning (bars removed) in which a tone signaled shock. The capacity of the tone to disrupt bar pressing was then assessed. 3. Bar pressing of rats previously injected with diazepam was more suppressed by the shock cue than that of rats previously injected with buspirone or saline. The long-term effects of buspirone and saline did not differ. 4. In Experiment 2, Lorazepam had effects different from diazepam during bar press training. Nonetheless, rats previously injected with Lorazepam were also more disrupted by a shock cue than were controls. 5. The results suggest that one long-term consequence of treatment with benzodiazepines may be hypersensitivity to behavioral disruption by stimuli that presumably elicit fear or anxiety.