EXPOSURE TO OZONE INHIBITS ISOLATION-INDUCED AGGRESSIVE-BEHAVIOR OF ADULT CD-1 MALE-MICE

Continuous exposure to ozone (O-3, 1.2 ppm) in adult CD-1 male mice fo r 20 consecutive days markedly influenced a number of items of aggress ive behavior induced by 59 days of individual housing. The behavior of mice was videotaped on days 1, 3, and 5 of five consecutive daily enc ounters (10 min each; isolation days 55, 57, and 59). Ozone exposure c aused an abatement of aggressive behavior and enhanced fear-associated displays shown by a significant decrease in the frequency of attackin g and digging and an increase in freezing. Moreover, O-3 induced a dec rease of time spent in attacking and exploration/activity. Nonexposed animals exhibited a day-dependent increase in self-grooming frequency which was not observed in O-3 mice; by contrast, freezing was higher i n O-3 mice on day 5 of the test. Data suggest that O-3 exposure produc es a remarkable reduction of mouse aggression, indirectly confirming p revious findings on physical and neurobehavioral effects of O-3. (C) 1 995 Wiley-Liss, Inc.