QUANTITATIVE AUTORADIOGRAPHY OF BETA-1 AND BETA-2-ADRENERGIC RECEPTORAND CELLULAR-LOCALIZATION OF MESSENGER-RNA FOR BETA-1 ADRENERGIC-RECEPTOR IN RAT-BRAIN

We have used both quantitative autoradiography to localize in rat brai n beta-1 and beta-2 adrenergic receptors and in situ hybridization to detect expression of beta-1 adrenergic receptor mRNA in rat brain. The receptors were labeled in vitro with H-3-dihydroalprenolol (H-3-DHA) that binds nonselectively to both beta-1 and beta-2 receptor subtypes. Selective inhibition of H-3-DHA binding with specific antagonists of beta-1 and beta-2 receptors allowed the visualization of beta-adrenerg ic receptor subtypes. High levels of beta-1 receptors were observed in the cingulate cortex, layers I-III of the cerebral cortex, hippocampu s, and thalamus. Oligonucleotide labeled with S-35-dATP was used for i n situ hybridization. High levels of beta-2 receptors were found in th e cerebellum. Approximately equal levels of beta-1 and beta-2 receptor s occurred in the midbrain including substantia nigra. The hybridizati on signal for beta-1 mRNA was strongest in cingulate and piriform cort ex, thalamic nuclei and light or moderate in somatosensory cortex and hippocampus. The pronounced differences in the ratio of beta-1 to beta -2 receptors among brain regions suggests that the subtypes of beta-ad renergic receptors may play different roles in neuronal function.