Diazepam Attenuates Scream Escape/avoidance Behavior in Rats

Abstract

Our concern is to investigate why a rat's scream can function as a negative reinforcer. To examine this issue, we focused on a rat's anxiety induced by another rat's scream. Rats were assigned to the scream group (n = 6), pure-tone group (n =6), and intense-tone group (n = 6). Each rat was placed in a shuttle-box (Fig. 1) for 10 minutes. While staying in one compartment, auditory stimuli were presented from the speakers placed on both ends of the shuttle-box, but no auditory stimuli were presented while a rat stays in another compartment. In the saline condition (1ml/kg), rats avoided being exposed to scream stimuli (65dB) and intense-tone stimuli (90dB), but did not avoid pure-tone stimuli (65dB). In the diazepam condition (2mg/1ml/kg), rats avoided being exposed to intense-tone stimuli, but did not avoid scream stimuli (Fig. 3). Thus, administration of the anti-anxiety drug selectively attenuated the scream avoidance behavior. These results suggest that the function of a rat's scream as a negative reinforcer is mediated by anxiety.