title: Specific decrease of high-affinity agonist states of alpha 2-adrenoceptors in the aging mouse brain.
abstract: Using the specific binding of the full alpha 2-adrenergic agonist 3H-UK-14,304 the contribution of high-affinity agonist states to the total number of alpha 2-adrenoceptors as labeled by the specific binding of the antagonist 3H-yohimbine has been investigated in the brain of young and aged mice. In contrast to findings with human platelet membranes, in young mice all central alpha 2-adrenoceptors are present in a high-affinity agonist conformation. While the total number of alpha 2-adrenoceptors was not changed in the brain of aged animals, a specific decline of the high-affinity agonist sites by about 30% was observed. It is suggested that the specific decrease of high-affinity agonist sites of central alpha 2-adrenoceptors might represent one of the mechanisms leading to a general impairment of central noradrenergic neurotransmission with aging.
authors.affiliation: Department of Psychopharmacology, Central Institute of Mental Health, Mannheim, Federal Republic of Germany.
authors.forename: C M
authors.initials: CM
authors.lastname: Gelbmann
authors.forename: W E
authors.initials: WE
authors.lastname: Müller
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000378:metabolism*; D000375:Aging / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000254:growth & development / Q000378:metabolism*; D000068438:Brimonidine Tartrate; D005260:Female; D051379:Mice; D011810:Quinoxalines / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism* / Q000502:physiology
chemical_list: D000316:Adrenergic alpha-Agonists; D011810:Quinoxalines; D011942:Receptors, Adrenergic, alpha; D000068438:Brimonidine Tartrate