The evidence for astrocytes as a target for central noradrenergic activity: expression of adrenergic receptors

Our recognition and understanding of adrenergic receptor expression by astrocytes and their cultured counterparts, astroglia, has occurred primarily over the past 2 decades. The advances in our knowledge have come about largely through the advent of new techniques with which to study neurotransmitter receptors, coupled with improvements in our ability to isolate, purify, and identify this central nervous system (CNS) cell type. The development of pharmacological tools such as second messenger assays, iodinated ligands, autoradiography, and intracellular electrophysiological recordings, paralleled that of cultured clonal cells lines of glial origin, purified astroglial primary cultures, isolations of astrocytes from adult tissues, and immunocytochemical staining for the astrocyte-specific glial fibrillary acidic protein (GFAP). As these techniques were combined and applied to the study of astrocyte pharmacology, our understanding of adrenergic receptor expression by these cells deepened. This review is an account of how these events have shaped our understanding of astrocytic adrenergic receptor expression.