抄録
Prolonged isolation from the early post-natal period may resalt in changes of brain composition such as receptor sensitivity enzyme activity as a resalt of a alterd monoamine turnover rate because of decreased neuronal activity following sensory deorivation. This change of composition may resalt in a behavioral change in isolated animals when the animals are exporsed to situations. If this hypothesis was demonstrated exparimentally, social isolation might become an interesting laboratory model for understanding the pathophysiology of psychosis like schizophrenia from the standpoint that psychosis consists of the interactions of both environmental influences and abnormal biological processes. The present study was undertaken to test this hypothesis. Male Wistar rats were isolated immediately after weaning for 12 weeks and exposed to electric foot shock of various intensities. The shock-elicited jumping behavior was measured every ten minutes for 1 hour. The frequency of jumping in isolated rats was lower than that in grouped and the difference between two groupes was the greatest with the most intence shock. In these experimental situations, there was no dignificant difference in monoamine turnover rate between the two groups while noradrenaline turnover markedly increased in both groups. Chlorpromazine supressed the jumping in a dose-dependent manner in both groups with stronger suppression in isolated rats. Methamphetamine facilitated the jumping in grouped rats dose-dependently while the drug rather depressed it in the isolated. From these results and the behavioral simikarity the isolated and 6-hydroxydopamine treated rats under foot shock situation, it was suggested that the receptor supersensitivity of central catecholamineragic neurons was involved in the behavioral change in isolated rats. Hopefully social isolation in rats might become an animal model of schizophrenia becaouse a considerable amount of the literatures on schizophrenia is concerned with the role of environment and experience in the pathogenesis and dopaminergic reseptor supersensitivity was noted recently about the pathophysicology of this disease.
