S-100 protein: regional CNS concentrations in rats raised in different environments.

The S-100 protein was measured in 7 discrete brain areas from rats raised in an enriched, social, or isolated environment for 21, 42, or 84 days after weaning. S-100 was measured at significantly higher concentrations under enriched than under social environmental conditions in cerebellum and brainstem at 21 days but not thereafter. The protein in corresponding areas of brain in isolates was significantly less concentrated than in social controls. The results suggest changes, in turnover of the protein as a result of stimulation and activation of functionally specific brain regions, of the animals' responses to and interaction with environmental stimuli and adaptation to those stimuli.