NMDA receptor modulation by D-cycloserine promotes episodic-like memory in mice.
BACKGROUND
NMDA-R (N-methyl-D-aspartate receptors) have been implicated in synaptic plasticity underlying one-trial learning of event-place associations. In rodents, episodic-like memory (ELM) of personally experienced events can be inferred from behavior that reflects the remembrance of the content (what kind of object was presented), place (where was this object placed), and temporal context (when was the object presented). We have previously shown that that D-cycloserine (DCS), an NMDA-R agonist, ameliorates stress-induced deficits in ELM.


OBJECTIVE
In this study, we used an experimental protocol designed to detect promnestic drug effects and investigated whether DCS, which is known to enhance learning and memory, can induce ELM under conditions where mice normally do not show ELM.


RESULTS
Mice that have been treated i.p. with DCS (20 mg/kg) both remembered the temporal order in which two different objects had been encountered during two consecutive sample trials, as well as their spatial position during the sample trials. Most importantly, the test trial performance of these mice is compatible with ELM in terms of an integrated memory for unique experiences comprising "what", "where", and "when" information. In contrast, mice that have received either a saline injection or lower doses of DCS (0.2 and 2.0 mg/kg) did not show such an integrated ELM.


CONCLUSIONS
To our knowledge, this is the first report showing that DCS can promote ELM in mice.
Zlomuzica
Armin
A
Center for Biological and Medical Research, Institute of Physiological Psychology, Heinrich-Heine University of Düsseldorf, 40225, Düsseldorf, Germany.
De Souza Silva
Maria A
MA
Huston
Joseph P
JP
Dere
Ekrem
E
D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D003523:Cycloserine / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D005556:Form Perception / Q000187:drug effects; D007274:Injections, Intraperitoneal; D008297:Male; D008568:Memory / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D011897:Random Allocation; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists*; D021641:Recognition, Psychology; D013028:Space Perception / Q000187:drug effects; D013998:Time Perception / Q000187:drug effects
D018690:Excitatory Amino Acid Agonists; D016194:Receptors, N-Methyl-D-Aspartate; D003523:Cycloserine