Modulation by D1 and D2 dopamine receptors of ATP-induced release of intracellular Ca(2+) in cultured rat striatal neurons.

摘要

The aim of the present study was to investigate, whether dopamine D1 and/or D2 receptors are able to interfere with the ATP-induced increase of the intracellular Ca(2+) concentration ([Ca(2+)](i)) in cultured striatal neurons identified by their morphological characteristics and their [Ca(2+)](i) transients in response to a high-K(+) superfusion medium. ATP appeared to release Ca(2+) mostly from an intracellular pool, since its effect was markedly depressed in the presence of cyclopiazonic acid, which is known to deplete such storage sites [Rubini, P., Pinkwart, C., Franke, H., Gerevich, Z., Norenberg, W., Illes, P., 2006. Regulation of intracellular Ca(2+) by P2Y(1) receptors may depend on the developmental stage of cultured rat striatal neurons. J. Cell. Physiol. 209, 81-93]. The mixed D1/D2 receptor agonist dopamine increased the ATP-induced [Ca(2+)](i) transients in a subpopulation of neurons. At the same time, dopamine did not alter the responses to K(+) in these cells. The selective D1 (SKF 83566) and D2 (sulpiride) receptor antagonists failed to modify the effect of ATP, but unmasked in the previously unresponsive neurons an inhibitory and facilitatory effect of dopamine, respectively. A combination of the two antagonists resulted in a failure of dopamine to modulate the [Ca(2+)](i) responses in any cell investigated. In conclusion, D1 and D2 receptors may modulate in an opposite manner the signalling pathways of P2Y(1) receptors in striatal neurons and thereby alter their development/growth or their cellular excitability and/or the release of GABA from their terminals.