Autoradiographic localization of binding sites for muscarinic and nicotinic agonists and antagonists on cultured astrocytes.

The cellular localization of cholinergic binding sites was studied in organotypic cultures of rat spinal cord and brain stem by means of autoradiography with radiolabelled muscarinic and nicotinic agonists and antagonists. Many astrocytes in both types of cultures showed intense labelling by 3H-acetylcholine in the presence of nicotine and the muscarinic antagonists 3H-pirenzepine, 3H-quinuclidinyl benzilate and 3H-propylbenzilcholine mustard. Incubation of the cultures with 3H-nicotine or 3H-acetylcholine in the presence of atropine also caused labelling of astrocytes. In addition to glial cells, many neurones showed binding of muscarinic and nicotinic agonists and antagonists. From our results it is suggested that astrocytes, besides neurones, possess both muscarinic and nicotinic receptors.