Elsevier

Neuroscience

Volume 56, Issue 1, September 1993, Pages 139-155
Neuroscience

Immunohistochemical localization ofα2a-adrenergic receptors in catecholaminergic and other brainstem neurons in the rat

https://doi.org/10.1016/0306-4522(93)90569-2Get rights and content

Abstract

α2A-Adrenergic receptors mediate a large portion of the known inhibitory effects of catecholamines on central and peripheral neurons. Molecular cloning studies have established the identity of threeα2A-adrenergic receptor genes from several species that encode the A, B and C subtypes of the receptor. The ratα2A-adrenergic receptor, as denned by sequence similarity, is the orthologue of the humanα2A-adrenergic receptor. In this paper, we report the development of rabbit antisera directed against a portion of the third intracellular loop of the ratα2A-adrenergic receptor and the histochemical localization ofα2A-adrenergic receptor-like immunoreactive material in the brainstem and spinal cord of the adult rat. Our antisera detectedα2A-adrenergic receptor-specific punctate staining associated with neuronal perikarya.α2A-adrenergic receptor-like immunoreactivity was widely, but heterogeneously, distributed in the brainstem and spinal cord, predominantly in areas involved in the control of autonomic function. Double labelling with antisera to tyrosine hydroxylase orphenylethanolamine-N-methyl-transferase revealed thatα2A-adrenergic receptor-like immunoreactivity is present in most, perhaps all, noradrenergic and adrenergic cells of the brainstem.α2A-adrenergic receptor-like immunoreactivity was detected in a small percentage of the dopaminergic cells of the A9 and A10 groups.

This study provides the first description of the specific immunohistochemical localization ofα2A-adrenergic receptors using a subtype-specific polyclonal antibody. The results support the view thatα2A-adrenergic receptors are involved in central cardiovascular control and suggest that the catecholaminergic autoreceptors of central noradrenergic and adrenergic neurons are the A subtype of the α2-adrenergic receptors.

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    §

    Present address: Dept. of Pharmacological and Physiological Sciences, 947 East 58th Street, University of Chicago, Chicago, IL 60637.

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