||Medetomidine, atipamezole, and guanfacine in delayed response performance of aged monkeys.
Studied the effects of a highly selective alpha-2 adrenergic agonist medetomidine (MED) and its antagonist atipamezole on the delayed response task performance (DRTP) of 5 15-26 yr old macaques. MED (1.0 μg/kg) improved the DRTP, whereas atipamezole had no effect on the DRTP at any dose. It has earlier been shown that alpha-2 adrenergic agonists clonidine and guanfacine (GUAN) improve age-associated memory impairment, but also contradictory effects of clonidine been reported. Clonidine and MED are much less selective than GUAN with respect to alpha-2A and alpha-2B receptor subtypes. Therefore, the effect of GUAN on the DRTP of the same Ss was studied in the same testing conditions to compare the effectiveness of these 2 alpha-2 adrenergic compounds. GUAN (0.0001 mg/kg) improved DRTP. Results show that alpha-2 agonists, independent of their different selectivity with respect to alpha-2A/2B receptor subtypes, are beneficial drugs in improving the DRTP. (PsycINFO Database Record (c) 2009 APA, all rights reserved)