The effect of propranolol dose and novelty of the reactivation procedure on the reconsolidation of a morphine place preference

• Published in: Behavioural brain research Vol. 216; no. 1; pp. 281 - 284
• Main Authors: Robinson, M.J.F., Ross, E.C., Franklin, K.B.J.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 2011; Elsevier
• Subjects: Adrenergic beta-Antagonists - administration & dosage; Analysis of Variance; Animals; Association Learning - drug effects; Behavioral psychophysiology; Biological and medical sciences; Conditioning (Psychology) - drug effects; Dose-Response Relationship, Drug; Drugs; Extinction; Extinction, Psychological - drug effects; Fundamental and applied biological sciences. Psychology; Male; Memory; Memory - drug effects; Morphine; Morphine - administration & dosage; Narcotics - administration & dosage; Novelty; Place conditioning; Place preferences; Propranolol; Propranolol - administration & dosage; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Long-Evans; Reconsolidation; Reward; Reconsolidation; Morphine; Place conditioning; Reward; Extinction; Memory; Reactivation; Conditioned place preference; Opiates; Narcotic analgesic; Antiarrhythmic agent; β-Adrenergic receptor; Antagonist; Conditioning; Propranolol; Beta blocking agent
• ISSN: 0166-4328; 1872-7549
• DOI: 10.1016/j.bbr.2010.08.009

Propranolol given after the first reactivation of a morphine-induced place preference prevents reconsolidation but it fails to do so if the first propranolol treatment occurs on a subsequent reactivation. Previously consolidated memories may become labile when they are reactivated and require reconsolidation. It has been suggested that when novel information is present at the time of memory reactivation reconsolidation is engaged but when no new information is present, reconsolidation may not occur, and extinction may be the dominant process instead. To test this idea we trained rats to associate a context with the rewarding properties of morphine (5 mg/kg, sc) over four conditioning pairings. Following training, animals were reactivated by a 30-min test session, once a day for 3 days. Rats were injected with the amnestic drug propranolol (10 or 40 mg/kg, sc) following reactivation either on the first or on the second day. They received saline on the alternate day. Propranolol disrupted reconsolidation for a conditioned place preference only when given on the first reactivation day, and this effect was more robust following the higher dose of propranolol. In contrast, animals given propranolol on the second reactivation day still displayed a preference for the morphine-paired context on the final test day. These results support the view that for memory to return to a labile state, the situation that evokes reactivation needs to be novel in some way. If the reactivation situation is familiar, reconsolidation may not occur.