Long-term isolation of Wistar rats alters brain monoamine turnover, blood corticosterone, and ACTH.

In this work, we investigated neurochemical parameters in the brain of male Wistar rats after isolation times (13 weeks) longer than those previously reported with this strain: a large majority of animals became muricidal under these conditions. Changes in monoamines turnover in hippocampus, cortex, and cerebellum and, in the blood, ACTH, and corticosterone were investigated. Monoamine turnover was analysed using two different approaches: first, by measuring neurotransmitter and metabolite levels and second, by measuring rate of accumulation of the precursor after decarboxylase. Both methods revealed a significant increase in catecholamine turnover in the three regions studied after the 13-week isolation; in contrast, only a modest elevation of 5-hydroxytryptophan accumulation was obtained in cortex and cerebellum of isolated rats. We also observed a decrease in corticosterone levels in blood concomitant with an increase of ACTH.