Characterization of histamine H 1-receptors on astrocytes in primary culture: [ 3H]mepyramine binding studies

Abstract

The characteristics of histamine H 1-receptors on astrocytes from the cerebral cortex of newborn rats in primary culture were analyzed with a [ 3H]mepyramine binding assay, and compared with those in the cerebral cortex. The apparent dissociation constant (K D) of [ 3H]mepyramine binding, the apparent inhibition constants (K i) of various H 1-ligands for [ 3H]mepyramine binding and the stereoselectivity of d- and l-chlorpheniramine for the inhibition of [ 3H]mepyramine binding to receptors on cultured astrocytes and to receptors in the brain tissue were very similar, indicating that these receptors are identical. The apparent density of H 1-receptors (B max) on astrocytes was 262 ± 60 fmol/mg protein, which was comparable to that in the brain tissue (194 ± 24 fmol/mg protein). The development of H 1-receptors on cultured astrocytes resembled the postnatal development of the receptors in the rat brain. These results suggest that astrocytes could be one of the main targets of the central histaminergic system.