Effect of P2 purinoceptor antagonists on kainate-induced currents in rat cultured neurons.
The action of purinergic antagonists on kainate-induced currents was studied in rat cortical neurons in primary culture using the whole-cell configuration of the patch-clamp technique. The amplitude of the currents induced by kainate in cortical neurons was concentration-dependent (EC(50)=106 microM). Pyridoxal-phosphate-6-azophenyll-2',4'-disulphonic acid 4-sodium (PPADS), a P2X antagonist, was ineffective in the reduction of the kainate-induced current in cortical neurons, while 2, 2'-pyridylisatogen (PIT), basilen blue (BB) and suramin, respectively two selective P2Y and a non-selective P2 receptor antagonist, caused a reduction in the amplitude of the current induced by kainate. BB decreased the inward current induced by kainate at all holding potentials and the reduction was dose-dependent (EC(50)=34 microM). The total conductance of the neurons for the kainate-induced current was significantly reduced (P<0.01) and the effect was completely reversible. BB furthermore reduced the kainate-induced current in granule and hippocampal neurons and decreased the amplitude of the alpha-amino-3-hydroxy-5-methyl-4-isoxalepropionic acid (AMPA)-evoked current in cortical neurons. Cholera toxin (ChTx) did not affect the action of BB on the kainate-induced currents in cortical neurons and moreover, when guanosine 5'-o-(3-thiotriphosphate) (GTPgammaS) was added to the electrode solution, the kainate-induced currents were still reduced by 100 microM BB. The maximal response to kainate decreased in the presence of 20 microM BB without changing its EC(50), indicating a non-competitive mechanism of inhibition. These results demonstrate that preferential P2Y receptor antagonists are able to modulate the kainate and AMPA-induced currents in central neurons, suggesting a potential use of these compounds as neuroprotective agents.
Zona
C
C
Cattedra di Fisiologia Umana, Dipartimento di Neuroscienze, Università degli Studi di Roma "Tor Vergata", Via di Tor Vergata, 135-00133, Roma, Italy. zona@med.uniroma2.it
Marchetti
C
C
Volontè
C
C
Mercuri
N B
NB
Bernardi
G
G
D000200:Action Potentials / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D002540:Cerebral Cortex; D004622:Embryo, Mammalian; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D006624:Hippocampus; D007608:Kainic Acid / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D058919:Purinergic P2 Receptor Antagonists; D051381:Rats; D017208:Rats, Wistar
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D058919:Purinergic P2 Receptor Antagonists; D007608:Kainic Acid