title: Impaired recovery of alpha 1- and alpha 2-adrenergic receptors in brain tissue of aged rats.
abstract: The influence of age on the rate of recovery of alpha 1- and alpha 2-adrenergic receptors was determined in rat brain following their irreversible inhibition by phenoxybenzamine (PBZ). Fischer 344 rats (3- or 24-months old) were administered two doses of vehicle or PBZ at 12-hour intervals. At various times after the last dose of PBZ, alpha-adrenergic receptors were quantified in washed membranes of cerebral cortex and hypothalamus, using [3H]prazosin and [3H]rauwolscine to label alpha 1- and alpha 2-adrenergic receptors, respectively. Recovery of prazosin binding sites in cortex and hypothalamus and of rauwolscine binding sites in cortex was significantly delayed in aged versus young rats. Administration of [3H]PBZ to young and aged rats revealed no apparent differences in the concentration or rate of disappearance of PBZ or its metabolites that could account for these age-related changes. These data suggest that the synthesis of both alpha 1- and alpha 2-adrenergic receptors is impaired in brain tissue from aged rats.
mesh_terms: D000375:Aging; D000818:Animals; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D002540:Cerebral Cortex / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D010643:Phenoxybenzamine / Q000494:pharmacology; D011224:Prazosin / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000378:metabolism
chemical_list: D011942:Receptors, Adrenergic, alpha; D010643:Phenoxybenzamine; D011224:Prazosin