Autoradiographic quantitation of beta-adrenergic receptors on neural cells in primary cultures. II. Comparison of receptors on various types of immunocytochemically identified cells.

We have developed a microcomputer-based video method to quantify neurotransmitter receptors on single, immunocytochemically labeled cultured cells. This method has been applied to determine whether beta-adrenergic receptors are more numerous on neurons, astroglia, oligodendroglia or fibroblasts in primary neural cell cultures, and to assess the heterogeneity of receptor expression within a single cell type. Dissociated cells from perinatal rat cerebral cortex were grown in very sparse cultures on polylysine-coated glass slides. The cultured cells were fixed and permeated, then stained with fluorescently labeled immunocytochemical markers for astroglia (glial fibrillary acidic protein), fibroblasts (fibronectin), oligodendroglia (galactocerebroside) or neurons (A2B5). beta-Adrenergic receptors were labeled with [125I]pindolol or [125I]cyanopindolol, and dry-mount autoradiography was carried out on the fixed cells. Cells were identified according to their morphology and cell-type specific staining, then autoradiographic grains associated with the defined cells were visualized by reflected polarized light microscopy and counted with a microcomputer-based video digitizing system. Using this technique, we have determined that fibroblasts have less than 15% of the number of beta-adrenergic receptors expressed by polygonal astroglia, whereas oligodendroglia and neurons had no detectable binding of 125I-labelled ligands. This suggests that in these mixed neural cell cultures, the great majority of beta-adrenergic receptors are associated with astroglia. Furthermore, we determined that process-bearing astroglia have less than 5% of the number of beta-adrenergic receptors expressed by polygonal astroglia. Since process-bearing astroglia are thought to be derived from polygonal astroglia, these results suggest that the beta-adrenergic receptor is lost from this population of astroglia during development.(ABSTRACT TRUNCATED AT 250 WORDS)