Impact of diazepam on fear-potentiated startle responses. Mean startle amplitude and percent fear-potentiated startle were examined after wild type (A, B), α1(H101R) (C, D), α2(H101R0 (E, F) and α3(H126R) (G, H) mice were administered diazepam (0, 1, 2 mg/kg) on Test. a=startle amplitude on Tone+Startle trials significantly different from both Leader and Startle Only trials. b=startle amplitude on Tone+Startle trials significantly different from Leader trials. c= startle amplitude on Tone+Startle trials significantly different from Startle Only trials. +=startle amplitude on Test Startle Only trials for mice that received drug significantly greater than the same trial type in mice treated with vehicle. **p<0.01.