ENVIRONMENTAL ENRICHMENT SELECTIVELY INCREASES 5-HT1A RECEPTOR MESSENGER-RNA EXPRESSION AND BINDING IN THE RAT HIPPOCAMPUS

Environmental enrichment augments neuronal plasticity and cognitive fu nction and possible mediators of these changes are of considerable int erest. In this study, male rats were exposed to environmental enrichme nt or single housing for 30 days. Rats from the enriched group had sig nificantly higher 5-HT1A receptor mRNA expression in the dorsal hippoc ampus (62%, 59% and 44% increase in the CA1, CA2 and CA3 subfields, re spectively). This was associated with significantly higher [H-3]8-OH-D PAT binding in the inferior part of CA1. No changes were seen for 5-HT 2A or 5-HT2C receptor mRNAs. The neuronal plasticity detected after en vironmental change may be mediated, in part, through 5-HT1A receptors. (C) 1998 Elsevier Science B.V.