EXPRESSION OF 5-HT7 RECEPTOR MESSENGER-RNA IN RAT-BRAIN DURING POSTNATAL-DEVELOPMENT

The present study is the first one to demonstrate the expression of 5- HT7 receptor mRNA by in situ hybridization during postnatal developmen t. No quantitative developmental changes in the 5-HT7 gene expression was observed in neocortex, pyramidal layers of CA1 and CA2, dentate gy rus, most of thalamic nuclei, mammillary region, superior colliculus a nd central gray. However, in retrosplenial cortex, subiculum and media l habenula an increase of labeling is observed between postnatal days (PN) PN15 and PN21. Striatum showed a transient expression during the first stages of development to be undetectable in adults. CA3 pyramida l cell layer, intramediodorsal thalamic nucleus and lateral habenula d isplayed a high mRNA expression at PN5 and PN8 which decreased through out development but it was still present in adults. A possible non-neu rotransmitter throphic function of 5-HT mediated through 5-HT7 recepto rs could be suggested. (C) 1997 Elsevier Science Ireland Ltd.