Kappa-opioid receptor in the rodent hippocampus: a comparative immunocytochemical study in the rat, guinea pig, hamster and gerbil.
Pre-embedding light microscopic immunocytochemistry, using a monoclonal antibody (mAb-KA8) raised against a frog brain kappa receptor preparation, recognising selectively the kappa-opioid receptor, was used for studying the occurrence, distribution, and species-specificity of the kappa-opioid receptor in the hippocampal formation of four rodent species (rat, guinea pig, hamster and gerbil). MAb-KA8 immunoreactivity was detectable in the rat, hamster and gerbil hippocampus, however the distribution of the labelled structures was heterogeneous. In the rat and hamster the hilus of dentate gyrus and the stratum oriens of the CA1 area contained immunoreactive cell bodies and proximal dendrites. In the gerbil mAb-KA8 immunopositive cell bodies were recognisable in the stratum radiatum of the CA1 and CA3 areas and in the subiculum. In the hamster varicose axon-like elements were also detected in the CA3 pyramidal layer. With the mAb-KA8 antibody there was no detectable kappa opioid receptor labelling in the hippocampus of the guinea pig. The results confirm the high degree of species-specific heterogeneity characterising the distribution of opioid peptides and their receptors in the hippocampal formation. The receptor was found in most cases postsynaptically, however in the hamster the immunopositive axons may refer to a presynaptic localisation.
Rácz
B
B
Department of Anatomy and Histology, Faculty of Veterinary Science, Szent István University, István u. 2, H-1078 Budapest, Hungary. bracz@univet.hu
Halasy
Katalin
K
D000818:Animals; D006224:Cricetinae; D006168:Guinea Pigs; D006624:Hippocampus / Q000166:cytology*; D007150:Immunohistochemistry / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D017473:Receptors, Opioid, kappa / Q000032:analysis*; D013045:Species Specificity
D017473:Receptors, Opioid, kappa