stressinduced impairment of inhibitory avoidance learning in female neuromedin b receptordeficient mice neuromedin b nmb is a mammalian bombesin bnlike peptide that exerts its function via the neuromedin b receptor nmbr the nmbnmbr system is involved in stress response and therefore we examined behavioral properties in female mice lacking nmbr using a restraintinduced 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 wildtype and nmbrdeficient mice using a onetrial passive avoidance test stressed nmbrdeficient mice exhibited a marked reduction in memory performance nmbrdeficient mice exhibited elevated spontaneous activity in a novel environment compared to nonstressed mutant mice after 30min stress and a similar difference was also observed between stressednonstressed wildtype mice an elevated plus maze test showed that the stress stimulus had no effect on anxiety in either wildtype or nmbrdeficient mice furthermore pain response of wildtype and nmbrdeficient mice induced by electric foot shock was not affected under either stressed or nonstressed conditions these results indicate that impaired memory performance in stressed nmbrdeficient mice is not a consequence of changes in spontaneous activity anxiety or pain response and suggest that the nmbnmbr pathway may play a role in regulating the stress response via the neural system that controls learning and memory