title: Differential involvement of the mu and kappa opioid receptors in spatial learning.
abstract: In order to test the role of mu and kappa opioid receptors (Mu opioid receptor (MOR) and Kappa opioid receptor (KOR)) in hippocampal-dependent spatial learning, we analyzed genetically engineered null mutant mice missing the functional MOR or KOR gene. Compared to wild-type mice, the homozygous MOR null mutants exhibited an impairment in the ultimate level of spatial learning as shown in two distinct tasks, the 8-arm radial-maze and the Morris water-maze. Control behaviors were normal. The learning impairment could be associated with the impairment we found in the maintenance of long-term potentiation in mossy fibers in CA3. In comparison, there was no impairment in spatial learning in our KOR mutants or in mossy fibers (mf) in CA3 region long-term potentiation (LTP). Our work suggests that the MOR may play a positive role in learning and memory by increasing LTP in CA3 neurons.
authors.affiliation: The Samuel Lunenfeld Research Institute at Mt. Sinai Hospital, and the Department of Molecular and Medical Genetics, University of Toronto, Ontario, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Jamot
authors.forename: H W D
authors.initials: HW
authors.lastname: Matthes
authors.forename: F
authors.initials: F
authors.lastname: Simonin
authors.forename: B L
authors.initials: BL
authors.lastname: Kieffer
authors.forename: J C
authors.initials: JC
authors.lastname: Roder
mesh_terms: D000818:Animals; D006624:Hippocampus / Q000502:physiology*; D017774:Long-Term Potentiation / Q000502:physiology; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D019599:Mossy Fibers, Hippocampal / Q000502:physiology; D017473:Receptors, Opioid, kappa / Q000502:physiology*; D017450:Receptors, Opioid, mu / Q000502:physiology*
chemical_list: D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu