The neurotransmitter-sensitive adenylate cyclases, respectively present in the dissociated cells of new-born mouse cerebral cortex (containing both neuronal and glial cells) and in a homogeneous population of glial cells, were compared. The dissociated cells from the cerebral cortex of new-born mice were found to contain Ca2+-, dopamine-, serotonin- and purinergic-sensitive adenylate cyclases. The dopaminergic receptor involved was extensively characterized and was similar to that described in adult animals. Beta-adrenergic-sensitive adenylate cyclase was present but was poorly active. After 3 weeks in culture, the neurons disappeared and a homogeneous population of glial cells was obtained (96% of the cells synthetized glial fibrillary acidic protein). These glial cells contained a highly potent beta-adrenergic-sensitive adenylate cyclase, and adenosine- adn Ca2+-sensitive enzymes. Ca2+ stimulation of the adenylate cyclase was due to the presence of calmodulin. We suggested that the dopaminergic- and serotoninergic-sensitive adenylate cyclases which disappeared during culture are probably localized in neuronal cells. The presence of Ca2+-, adenosine- and beta-adrenergic-sensitive adenylate cyclases in glial cells does not exclude their presence in neuronal cells. For comparison, the same experiments were conducted on meningeal layers of new-born mice and on meningeal cells in culture. They both contained beta-adrenergic- and purinergic-sensitive adenylate cyclases.