The effects of repeated administration of fluprazine on target biting and intruder-evoked attacks

The effects of repeated administration of fluprazine, an "aggression"-reducing drug, 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 six times with an average latency to the first attack of 258 s. In the prechronic dose-response curve determination, 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. During the chronic administration of the ED50 dose of fluprazine, intershock interval target biting gradually increased to a level equal to those subjects receiving chronic saline. Moreover, a shift (to the right) in the during-chronic fluprazine dose-response curve for postshock and intershock interval target biting, was observed. Likewise, during the chronic administration of the ED50 dose of fluprazine, resident number of attacks gradually increased to a level equal to those subjects receiving chronic saline. However, no shift in the during-chronic dose-response curve was observed in subjects tested in this paradigm.