Abstract: Male rats were isolated or housed in groups for 9-12 weeks. Then acuteand chronic acoustic stimuli were given. The influences of social isolation onthe incidence of audiogenic epilepsy and adaptation process in rats wereobserved and the brain contents of monoamines were determined. The incidence of audiogenic epilepsy was higher in isolated rats than ingregarious rats during 20 minutes acute acoustic stimulus. The brain contentsof NE decreased significantly in the telencephalon of the isolated animals afteracoustic stress. But it just tended to decrease in the telencephalon of thegregarious rats and in the brain stem of both isolated and gregarious rats. The decrease of the incidence of audiogenic epilepsy in isolated rats wasslower than that of the gregarious rats during daily 20 minutes acousticstress for 6 days. The total numbers of epilepsy and wild running-about inthe period of 6 days in isolated rats were markedly more than that of thegregarous rats. The brain contents of NE in the brain stem of the isolatedrats were significantly lower than in the gregarious rats after chronic auditorystress for 6 days. Brain contents of 5-HT both in the telencephalon and thebrain stem increased in gregarious rats, but it only increased in thetelencephalon of the isolated rats. On the 7th day the brain contents of NE inthe telencephalon of the gregarious rats increased significantly and the braincontents of 5-HIAA increased in isolated rats. The present results indicated that the isolated animals were weaker incoping with auditory stress, their adaptation process also slowed down. Thechanges of brain contents of monoamines after auditory stress suggest that alower rate of synthesis of NE and 5-HT in isolated animals may beresponsible for such phenomena.

Key words: NULL