Autoradiographic localization of binding sites for vasoactive intestinal peptide and angiotensin II on neurons and astrocytes of cultured rat central nervous system.

The cellular localization of binding sites for [125I] vasoactive intestinal polypeptide and [3H]angiotensin II was studied in explant cultures of rat spinal cord, brain stem, cerebellum and cortex by means of autoradiography. In spinal cord cultures, interneurons of the dorsal horn and motoneurons of the ventral horn were labelled by [125I]vasoactive intestinal polypeptide and [3H]angiotensin II. In many brain stem cultures, groups of large neurons revealed intense binding of both peptides. In contrast, only few medium-sized cerebellar neurons, probably interneurons, showed binding sites for [125I]vasoactive intestinal polypeptide and [3H]angiotensin II. Furthermore, the intensity of labelling of cerebellar neurons was usually weaker than that of neurons of the brain stem and spinal cord. Many neurons in cultures of neocortex were also labelled by [125I]vasoactive intestinal polypeptide, whereas little binding was found with [3H]angiotensin II. In addition to neurons, binding sites for both peptides were also observed on astrocytes. Labelling of these cells was more intense in spinal cord and brain stem cultures than in cultures of cerebellum and cortex, suggesting that only a certain type or a certain population of astrocytes possesses receptors for vasoactive intestinal polypeptide and angiotensin II, or that glial cells in different parts of the CNS have different physiological and pharmacological properties.