M. Mackowiak et al., c-Fos proteins, induced by the serotonin receptor agonist DOI, are not expressed in 5-HT2A positive cortical neurons, MOL BRAIN R, 71(2), 1999, pp. 358-363
In the present study, we tried to find out whether the expression of c-Fos
proteins induced by DOI, an agonist of 5-HT2A/2C receptor subtypes is coloc
alized with 5-HT2A receptor protein in cortical neurons. 5-HT2A receptor pr
otein was found in two major neuronal elements: dendritic processes (seen i
n layers II/III-V) and less abundantly in cell bodies (layer V). In our exp
eriment, DOI (8 mg/kg) induced a robust appearance of c-Fos proteins mainly
in neuronal nuclei of the upper part of layer V/IV, and a moderate amount
of sparsely distributed nuclei in deep cortical layers (V and VI). It was f
ound that c-Fos proteins never occurred in cortical neurons, which were imm
unopositive for the presence of 5-HT2A receptor protein. It is concluded th
at the induction of c-Fos proteins expression by DOI though initiated by ac
tivation of 5-HT2A receptors, requires the involvement of intermediate neur
otransmitter(s). Additionally, our study indicates that the appearance of D
OI-induced c-Fos proteins cannot be used as a simple and direct marker of l
ocalization and site of activation of 5-HT2A receptors. (C) 1999 Elsevier S
cience B.V. All rights reserved.