Colocalization of binding sites for somatostatin, muscarine and nicotine on cultured neurones of rat neocortex, cerebellum, brain stem and spinal cord: Combined autoradiographic and immunohistochemical studies

The cellular localization of binding sites for [ 125I]1-tyramine somatostatin ([ 125I]SS) was studied in explant cultures of rat CNS by autoradiography. In cultures from cortex, brain stem and spinal cord many neurones revealed binding sites for the peptide whereas in cerebellar cultures only little binding of [ 125I]SS was observed. In addition to neurones, astrocytes were also labelled by the peptide. By combined immunohistochemical and autoradiographic techniques, it was demonstrated that the majority of neurones which expressed binding sites for [ 125I]SS were also immunostained by the monoclonal cholinergic muscarinic or nicotinic receptor antibodies (M 35 and W 6, respectively), providing evidence for a colocalization of cholinergic and somatostatin receptors on the neuronal membrane.