Effects of haloperidol on communicative and aggressive behavior in male mice with different experiences of aggression

Effects of two doses of haloperidol(0.1 and 0.4 mg/kg, 30 min and 24 h, IP) on communicative and aggressive behavior in C57BL/6J male mice have been s tudied. Some of the mice were without prior experience of aggression ("recr uits"); the others had been victorious in 20 daily aggressive confrontation s ("experienced winners"). Communicative behavior was estimated as the beha vioral reaction to a standard tester (loser) in the partition test. Haloper idol in either dose significantly reduced communicative behavior in the "re cruits," but not in the "experienced winners." Significantly fewer attacks, less total attacking time, and total time of aggressive behavior (aggressi ve grooming + attacks) were demonstrated by the "experiences winners," than by the "recruits," while the latency of the first attack, the number, the total and average duration of aggressive grooming events were significantly higher. In the "recruits," haloperidol dose dependently increased the late ncy and decreased the number of attacks, the total attacking time, and the total time of aggressive behavior 30 min and 24 h after injection. However, haloperidol did not affect the average or total time of aggressive groomin g. Neither dose significantly affected any measure of aggressive behavior i n the "experienced winners." It has been concluded that repeated aggression experience reduces the pharmacological sensitivity of the dopamine recepto rs. (C) 1999 Elsevier Science Inc.