Similar ultrastructural distribution of the 5-HT2A serotonin receptor and microtubule-associated protein MAP1A in cortical dendrites of adult rat
Section snippets
5-HT2A and MAP1A antibodies
Three 5-HT2A receptor antibodies were used. (1) A monoclonal antibody commercially available at Pharmingen (San Diego, CA, USA). This antibody was produced and characterized by Wu et al. (1998), using a GST fusion protein antigen containing the entire N-terminal domain (1–76) of the cloned human 5-HT2A receptor sequence. The targeted epitope is the sequence comprised between residues 64 and 76 (TCLSILHLQEKNW; C. Wu, personal communication). (2) A polyclonal antibody directed against a peptide
Subcellular distribution of 5-HT2A receptors in cortical dendrites
At the light microscopic level, the regional distribution of the immunoreactivity after labeling with every one of the three 5-HT2A receptor antibodies was the same as previously described in detail following immunostaining with the monoclonal N-terminal antibody (Cornea-Hébert et al., 1999a). In the frontoparietal cortex, a laminar pattern was observed. In layer V strong labeling of pyramidal neuronal somata and of their apical dendrites, spanning across the upper layers and branching
Discussion
The present immunoelectron microscopic study confirmed the prominent intracellular localization of 5-HT2A receptors in dendrites of the cerebral cortex. After immunogold labeling with two antibodies against their N-terminal portion, and a third against their C-terminal portion, the apportionment of 5-HT2A receptors in a plasma membrane and an intracellular compartment was equivalent to the relative surface area of these compartments, excluding any significant enrichment of the plasma membrane.
Acknowledgements
This work was supported by a studentship from the Groupe de recherche sur le système nerveux central (FCAR) to V.C.-H., Grant MT-3544 from the Medical Research Council of Canada (now NRF 3544 from CIHR) to L.D., and Grants RO1MH 61887 and KO2MH 01366 from NIH to B.L.R. The authors are indebted to Chun Wu and Sujay K. Singh for their generous gift of the Pharmingen 5-HT2A antibody. They also thank Gaston Lambert and Jean Léveillé for expert photographic work.
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