Localization of P2X receptors in the guinea pig adrenal gland

The distribution of each of the seven subtypes of adenosine 5'-triphosphate (ATP)-gated P2X receptors was investigated in the adrenal gland of guinea pig utilizing immunohistochemical techniques. The occurrence of positive immunoreactivity with specific distribution was observed for antibodies against P2X(1), P2X(2), P2X(5) and P2X(6) receptors, whereas no immunoreactivity was found for antibodies against P2X(3), P2X(4) and P2X(7) receptors. Immunoreactivity for P2X(1) occurred in cells of the inner region of the zona reticularis of the cortex, Several P2X(2)-immunoreactive connective tissue-like elements were located between groups of cortical cells of the zona reticularis. Bundles and terminals of nerve fibres as well as intrinsic neurones gave positive immunoreactivity for P2X(5). The immunoreactive nerve fibres appeared to belong to both extrinsic preganglionic sympathetic and intrinsic immunoreactive neurones. Chromaffin cells were immunoreactive for the P2X(6) receptor antibody. The widespread and specific distribution of P2X receptor subtypes in the adrenal gland suggests significant roles for purinergic signalling in the physiology of the guinea pig adrenal gland.