Expression of P2X receptors in the rat anterior pituitary.

In this study, the distribution patterns of P2X1 to P2X7 receptors in the anterior pituitary cells of rat were studied with single-, double-, and triple-labeling immunofluorescence, combined method of immunofluorescence and in situ hybridization, and Western blot. The results showed that the expression level of the P2X4 receptor protein was highest, followed by P2X5, P2X3, P2X2, P2X6, and P2X7 receptor proteins, but no P2X1 receptor protein was detected. Strong P2X4 receptor-immunoreactivity was detected in almost all the anterior pituitary cells. Different combinations of P2X receptors were detected in each individual cell type of the rat anterior pituitary. Gonadotrophs express P2X4, P2X5, and P2X6 receptors. Corticotrophs express P2X3 and P2X4 receptors. Folliculo-stellate cells express P2X2 and P2X4 receptors, and somatotrophs, lactotrophs, and thyrotrophs express only P2X4 receptors. The macrophages with Iba-1-ir expressed P2X7 receptors. The possible functions of these P2X receptors in each individual cell type of the rat anterior pituitary are discussed.