title: Adenosine A1 and A2A receptors are co-expressed in pyramidal neurons and co-localized in glutamatergic nerve terminals of the rat hippocampus.
abstract: Adenosine is a neuromodulator that controls neurotransmitter release through inhibitory A1 and facilitatory A2A receptors. Although both adenosine receptor-mediated inhibition and facilitation of glutamate release have been observed, it is not clear whether both A1 and A2A receptors are located in the same glutamatergic nerve terminal or whether they are located on different populations of these terminals. Thus, we have tested if single pyramidal glutamatergic neurons from the hippocampus simultaneously expressed A1 and A2A receptor mRNA and if A1 and A2A receptors were co-localized in hippocampal glutamatergic nerve terminals. Single cell PCR analysis of visually identified pyramidal neurons revealed the simultaneous presence of A1 and A2A receptor mRNA in four out 16 pyramidal cells possessing glutamatergic markers but not GABAergic or astrocytic markers. Also, A1 and A2A receptor immunoreactivities were co-localized in 26 +/- 4% of nerve terminals labeled with antibodies against vesicular glutamate transporters type 1 or 2, i.e. glutamatergic nerve terminals. This indicates that glutamatergic neurons in the hippocampus co-express A1 and A2A receptors and that these two receptors are co-localized in a subset of glutamatergic nerve terminals.
authors.affiliation: Center for Neurosciences of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: N
authors.initials: N
authors.lastname: Rebola
authors.forename: R J
authors.initials: RJ
authors.lastname: Rodrigues
authors.forename: L V
authors.initials: LV
authors.lastname: Lopes
authors.forename: P J
authors.initials: PJ
authors.lastname: Richardson
authors.forename: C R
authors.initials: CR
authors.lastname: Oliveira
authors.forename: R A
authors.initials: RA
authors.lastname: Cunha
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D007150:Immunohistochemistry; D008297:Male; D026901:Membrane Transport Proteins / Q000378:metabolism; D009411:Nerve Endings / Q000378:metabolism* / Q000648:ultrastructure; D017966:Pyramidal Cells / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D043682:Receptor, Adenosine A1 / Q000096:biosynthesis*; D043705:Receptor, Adenosine A2A / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050598:Vesicular Glutamate Transport Protein 1; D050599:Vesicular Glutamate Transport Protein 2
chemical_list: D026901:Membrane Transport Proteins; D043682:Receptor, Adenosine A1; D043705:Receptor, Adenosine A2A; C493475:Slc17a6 protein, rat; D050598:Vesicular Glutamate Transport Protein 1; D050599:Vesicular Glutamate Transport Protein 2; D018698:Glutamic Acid