title: P2X2 and P2Y1 immunofluorescence in rat neostriatal medium-spiny projection neurones and cholinergic interneurones is not linked to respective purinergic receptor function.
abstract: 1. The presence of ionotropic P2X receptors, targets of ATP in fast synaptic transmission, as well as metabotropic P2Y receptors, known to activate K(+) currents in cultured neostriatal neurones, was investigated in medium-spiny neurones and cholinergic interneurones contained in neostriatal brain slices from 5-26-day-old rats. 2. In these cells, adenosine-5'-triphosphate (ATP) (100-1000 microm), 2-methylthioadenosine-5'-triphosphate (2MeSATP), alpha,beta-methyleneadenosine-5'-triphosphate (alpha,betameATP, 30-300 microm, each) and adenosine-5'-O-(3-thiotriphosphate (ATPgammaS) (100 microm) failed to evoke P2X receptor currents even when 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 0.1 microm), apyrase (10 U ml(-1)) or intracellular Cs(+) was used to prevent occluding effects of the ATP breakdown product adenosine, desensitisation of P2X receptors by endogenous ATP and an interference with the activation of K(+) channels, respectively. P2X receptor agonists were also ineffective in outside-out patches withdrawn from the brain slice tissue. Muscimol (10 microm) evoked GABA(A) receptor-mediated currents under all these conditions. 3. When used as a control, locus coeruleus neurones responded with P2X receptor-mediated currents to ATP (300 microm), 2MeSATP and alpha,betameATP (100 microm, each). 4. ATP and adenosine-5'-diphosphate (ADP) (100 microm, each) did not activate K(+) currents in the neostriatal neurones. 5. Despite the observed lack of function, P2X(2) and P2Y(1) immunofluorescence was found in roughly 50% of the medium-spiny neurones and cholinergic interneurones. 6. A role of ATP in synaptic transmission to striatal medium-spiny neurones and cholinergic interneurones appears unlikely, however, the otherwise silent P2X and P2Y receptors may gain functionality under certain yet unknown conditions.
authors.affiliation: Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, Härtelstrasse 16-18, D-04107, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Scheibler
authors.forename: Mihail
authors.initials: M
authors.lastname: Pesic
authors.forename: Heike
authors.initials: H
authors.lastname: Franke
authors.forename: Robert
authors.initials: R
authors.lastname: Reinhardt
authors.forename: Kerstin
authors.initials: K
authors.lastname: Wirkner
authors.forename: Peter
authors.initials: P
authors.lastname: Illes
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Nörenberg
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology / Q000502:physiology; D000818:Animals; D048429:Cell Size; D005455:Fluorescent Antibody Technique; D018755:GABA Agonists / Q000494:pharmacology; D066298:In Vitro Techniques; D007395:Interneurons / Q000201:enzymology / Q000378:metabolism*; D008125:Locus Coeruleus / Q000166:cytology / Q000201:enzymology / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology; D018613:Microscopy, Confocal; D009118:Muscimol / Q000494:pharmacology; D017072:Neostriatum / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D009434:Neural Pathways / Q000187:drug effects / Q000201:enzymology; D009474:Neurons / Q000201:enzymology / Q000378:metabolism*; D010275:Parasympathetic Nervous System / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D058910:Purinergic P2 Receptor Agonists; D051381:Rats; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058476:Receptors, Purinergic P2X2; D058472:Receptors, Purinergic P2Y1; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
chemical_list: D018755:GABA Agonists; C546403:P2rx2 protein, rat; C546384:P2ry1 protein, rat; D058910:Purinergic P2 Receptor Agonists; D018048:Receptors, Purinergic P2; D058476:Receptors, Purinergic P2X2; D058472:Receptors, Purinergic P2Y1; D009118:Muscimol; D000255:Adenosine Triphosphate