Expression of P2X receptors in rat choroid plexus.

In this study, we have used reverse transcriptase polymerase chain reaction and immunocytochemistry to show that P2X1, P2X2, P2X4, P2X5, P2X6 and P2X7 receptor messenger RNA and protein are expressed in the rat choroid plexus taken from the fourth and lateral ventricles. In some epithelial cells, the apical surfaces were stained more intensely than the basal surfaces. Some of the epithelial cells showed strong staining, others weak or no staining. Double immunostaining with P2X and cytokeratin antibodies or isolectin B4 binding confirmed that P2X receptors were localized in subpopulations of the choroid plexus epithelial cells, rather than the endothelial cells of capillaries. The results suggest that P2X receptors might be involved in the regulation of cerebrospinal fluid composition.