Open AccessNoradrenergic alpha 1 and alpha 2 receptors: light microscopic autoradiographic localization.
Author(s) -
W. Scott Young,
MJ Kuhar
Publication year - 1980
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.77.3.1696
Subject(s) - receptor , locus ceruleus , alpha (finance) , endocrinology , adrenergic receptor , medicine , hypothalamus , olfactory bulb , nucleus , central nervous system , chemistry , locus coeruleus , neuroscience , biology , dopamine , substantia nigra , construct validity , nursing , dopaminergic , patient satisfaction
[3H]WB-4101 and p-[3H]aminoclonidine were used for light microscopic autoradiographic localization of alpha 1 and alpha 2 adrenergic receptors, respectively, in the rat brain. The binding of these ligands to slide-mounted tissue sections had all of the characteristics associated with alpha 1 and alpha 2 receptors. It was saturable with appropriate kinetic constants and was blocked only by other alpha-adrenergic drugs with the appropriate potency. Autoradiographic studies revealed a distribution of alpha-adrenergic receptors throughout the nervous system. Certain areas had elevated levels. These included parts of the olfactory bulb and nucleus, parts of the cerebral cortex and dentate gyrus, the more medial portions of the hypothalamus and thalamus, the locus ceruleus and nucleus tractus solitarii, and parts of the spinal cord. In certain areas, the distribution of alpha 1 and alpha 2 receptors was markedly different. These results provide some rational basis for the observed actions of alpha-adrenergic drugs on the central nervous system. For example, the finding of high densities of alpha 2 receptors in the nucleus tractus solitarii is most likely related to its antihypertensive action. The observed codistribution of alpha 2 receptors with opiate receptors would provide an explanation of the observation that alpha 2 agonists block opiate withdrawal. The results are also discussed in relationship to the anatomy of catecholamine systems in the brain.