title: Stress-induced impairment of inhibitory avoidance learning in female neuromedin B receptor-deficient mice.
abstract: Neuromedin B (NMB) is a mammalian bombesin (BN)-like peptide that exerts its function via the neuromedin B receptor (NMB-R). The NMB/NMB-R system is involved in stress response, and therefore we examined behavioral properties in female mice lacking NMB-R using a restraint-induced stress paradigm. Thirty minutes of restraint in a wire mesh cage constituted a sufficient stress stimulus for mice as evidenced by elevated blood glucose concentrations in stressed wild-type and NMB-R-deficient mice. Using a one-trial passive avoidance test, stressed NMB-R-deficient mice exhibited a marked reduction in memory performance. NMB-R-deficient mice exhibited elevated spontaneous activity in a novel environment compared to non-stressed mutant mice after 30-min stress, and a similar difference was also observed between stressed/non-stressed wild-type mice. An elevated plus maze test showed that the stress stimulus had no effect on anxiety in either wild-type or NMB-R-deficient mice. Furthermore, pain response of wild-type and NMB-R-deficient mice induced by electric foot shock was not affected under either stressed or non-stressed conditions. These results indicate that impaired memory performance in stressed NMB-R-deficient mice is not a consequence of changes in spontaneous activity, anxiety, or pain response, and suggest that the NMB/NMB-R pathway may play a role in regulating the stress response via the neural system that controls learning and memory.
authors.affiliation: Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan. kaz-yamada@brain.riken.go.jp
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Yamada
authors.forename: Yuko
authors.initials: Y
authors.lastname: Santo-Yamada
authors.forename: Keiji
authors.initials: K
authors.lastname: Wada
mesh_terms: D000818:Animals; D001362:Avoidance Learning; D001786:Blood Glucose / Q000032:analysis; D004597:Electroshock; D005260:Female; D005838:Genotype; D018782:Maze Learning; D008661:Metabolism, Inborn Errors / Q000503:physiopathology; D051379:Mice; D009043:Motor Activity; D010146:Pain / Q000503:physiopathology; D018004:Receptors, Bombesin / Q000172:deficiency*; D012149:Restraint, Physical; D013312:Stress, Physiological / Q000503:physiopathology / Q000523:psychology*
chemical_list: D001786:Blood Glucose; D018004:Receptors, Bombesin