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Astrocytes cultured from specific brain regions differ in their expression of adrenergic binding sites

1990; Elsevier BV; Volume: 517; Issue: 1-2 Linguagem: Inglês

10.1016/0006-8993(90)91027-e

1872-6240

Paul Ernsberger, Lorraine Iacovitti, Donald J. Reis,

Neonatal and fetal brain pathology

We sought to characterize regional heterogeneity of astrocytes using adrenergic receptor sites as cellular markers. Primary cultures made from 6 regions of neonatal rat brain consisted almost exclusively of astrocytes. Membranes from astrocytes cultured 1–3 weeks were prepared for radioligand binding assays of β- and α2-adrenergic sites using the ligands [3H]dihydraalprenolol and [3H] p-aminoclonidine, respectively. Receptor expression was not affected by time in culture. Astrocytes from different brain regions varied up to 3-fold with respect to number but not affinity for both classes of adrenergic binding site with a rank order of cerebral cortex = superior colliculus > hippocampus = ventral midbrain⩾caudate nucleus⩾hypothalamus. Binding to β- and α2-adrenergic receptors was positively correlated across brain regions. Astrocytic receptor binding in each region did not correspond to total receptor levels assessed by quantitative autoradiography. We conclude that: (a) astrocytes are markedly heterogeneous between major brain regions with respect to expression of adrenergic binding sites; (b) regional variations in the density of adrenergic binding sites in brain reflect, in part, local specialization of astrocytes; and (c) a substantial proportion of the adrenergic binding sites in some brain regions may be on astrocytes.