P2X2 and P2Y1 immunofluorescence in rat neostriatal medium-spiny projection neurones and cholinergic interneurones is not linked to respective purinergic receptor function.
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 P2X receptor agonists were also ineffective in outside-out patches withdrawn from the brain slice tissue.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.
Scheibler
Peter
P
Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, Härtelstrasse 16-18, D-04107, Germany.
Pesic
Mihail
M
Franke
Heike
H
Reinhardt
Robert
R
Wirkner
Kerstin
K
Illes
Peter
P
Nörenberg
Wolfgang
W
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
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