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Alpha‐adrenergic receptor, subtype 2A (α_2A‐AR), activation is one of the primary modes of action for norepinephrine (NE) in the rat hippocampal formation. In this study, α_2A‐AR immunoreactivity (α_2A‐AR‐I) was localized by light and electron microscopy in the rat hippocampus and dentate gyrus by using a previously characterized antibody to the rat α_2A‐AR. By light microscopy, dense α_2A‐AR‐I was observed in the pyramidal and granule cell layers. Diffuse and slightly granular α_2A‐AR‐I was found in the neuropil in all other laminae, notably stratum lacunosum‐moleculare. Ultrastructurally, α_2A‐AR‐I was found in neuronal cytoplasm associated with large multivesicular‐like organelles and with clusters adjacent to endoplasmic reticula and/or plasmalemma. The distribution of α_2A‐AR‐I in the strata oriens, radiatum, and lacunosum‐moleculare of hippocampal CA1 and CA3 regions and in the molecular layer of …