Mind the gap: delayed manifestation of long-term object memory improvement by phosphodiesterase inhibitors.
We examined the temporal profile of pharmacologically enhanced episodic memory, using the object recognition task. Male Wistar rats were tested at different retention intervals ranging from 1 h to 24 h. The object discrimination performance of all groups (untreated, placebo, drug treatment) gradually decreased up to an interval (8 h). Interestingly, only after this 8 h interval the memory improving effects of vardenafil and rolipram started to emerge. This time-dependent memory performance shows similarities with the Kamin effect. The delayed manifestation of drug-enhanced memory suggests that two separate memory mechanisms are at play, a quick transient form of memory and a more stable memory form that requires several hours to develop. It is important to take this into account when testing treatments intended for long-term memory enhancement.
Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands; European Graduate School of Neuroscience (EURON), Maastricht, The Netherlands.
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Akkerman
Department of Neuropsychology and Psychopharmacology, Maastricht University, Maastricht, The Netherlands; European Graduate School of Neuroscience (EURON), Maastricht, The Netherlands.
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Blokland
Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands; European Graduate School of Neuroscience (EURON), Maastricht, The Netherlands. Electronic address: jos.prickaerts@maastrichtuniversity.nl.
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Prickaerts
D000818:Animals; D008297:Male; D061212:Memory, Episodic; D057567:Memory, Long-Term / Q000187:drug effects*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D021641:Recognition, Psychology / Q000187:drug effects*
D010726:Phosphodiesterase Inhibitors
Behavior; Memory; Phosphodiesterase; Rat; Recognition