title: Morphine state-dependent learning: interactions with alpha2-adrenoceptors and acute stress.
abstract: The interactions of -adrenoceptors and acute restraint stress with morphine state-dependent memory of passive avoidance were examined in mice. Memory acquired following pre-training morphine administration (5 mg/kg, i.p.) was dose- and time-dependently retrieved by pre-test morphine; this effect was reversible by yohimbine (1 mg/kg). Pre-test clonidine (0.005-0.1 mg/kg) was also effective in restoring morphine-induced memory. Pre-training clonidine (2 mg/kg) induced an amnestic effect that was restorable by pre-test clonidine or morphine; this effect was also blocked by yohimbine. Acute pre-training stress for 2 h induced an amnestic effect that was reversible by pre-test morphine (1 and 5 mg/kg) or clonidine (0.01 and 0.1 mg/kg). Finally, acute pre-test stress could restore the impairment of memory induced by pre-training morphine. The data are suggestive of a functional interaction between -opioid, -adrenergic receptors and stress in modulating state-dependent learning and memory.
authors.affiliation: Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: H
authors.initials: H
authors.lastname: Homayoun
authors.forename: S
authors.initials: S
authors.lastname: Khavandgar
authors.forename: M R
authors.initials: MR
authors.lastname: Zarrindast
mesh_terms: D000208:Acute Disease; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D003000:Clonidine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D008297:Male; D008568:Memory / Q000187:drug effects; D051379:Mice; D009020:Morphine / Q000494:pharmacology*; D009294:Narcotics / Q000494:pharmacology*; D011930:Reaction Time; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism*; D017450:Receptors, Opioid, mu / Q000378:metabolism; D012149:Restraint, Physical; D013312:Stress, Physiological / Q000523:psychology*; D013997:Time Factors; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D009294:Narcotics; D018341:Receptors, Adrenergic, alpha-2; D017450:Receptors, Opioid, mu; D015016:Yohimbine; D009020:Morphine; D003000:Clonidine