Diazepam attenuates conditioned odor potentiation of startle in rats

Recently Richardson, Vishney, and Lee (1999) described a simple protocol whereby conditioned odor potentiation of startle (OPS) could be observed in rats. The aim of the present study was to extend their findings by determining whether OPS is attenuated by pretest intraperitoneal injection of diazepam. The results showed that diazepam (0.6 mg/kg) markedly attenuated OPS at test (Experiment 1) and that this attenuation was not due to diazepam's affecting either odor detection or mobility (Experiment 2). The results suggest not only that the OPS effect is mediated by fear, but also that it may be mediated by the same neural substrates that mediate conditioned tone and conditioned light potentiated startle.