Effects of fluprazine (DU27716) and ethanol on target biting behavior and intruder-evoked attacks.

The effects of an "aggression"-reducing drug, fluprazine, and an "aggression"-enhancing drug, ethanol, were evaluated in mice using the target biting and resident-intruder paradigms. Under baseline conditions there was a high target biting rate immediately after the delivery of a 2.0 mA tail shock, an intermediate target biting rate during a 2-min intershock interval, and a low target biting rate during a 15-s tone stimulus which signaled the shock. During the 10-min resident intruder test sessions, resident males attacked bulbectomized intruders an average of 11.3 times with an average latency to the first attack of 68.3 s. Fluprazine caused a dose-dependent decrease in postshock and intershock interval target biting behavior, increased the latency to the first attack, and decreased the number of attacks in the intruder-evoked aggression paradigm. Ethanol exerted a biphasic effect in both paradigms. A dose of 0.5 g/kg increased and 4.0 g/kg decreased intershock interval target biting behavior. Likewise, ethanol at a dose of 1.0 g/kg increased the number of intruder-evoked attacks and 0.5 g/kg reduced the latency to the first attack whereas 2.0 g/kg ethanol reduced the number of intruder-evoked attacks. These observations are discussed in reference to the specificity with which different drugs and paradigms are able to dissociate offensive versus defensive aggression.