Characterization of Neuropeptide Y, Y2 Receptor Knockout Mice in Two Animal Models of Learning and Memory Processing

Neuropeptide Y (NPY) and, in particular, the Y^sub 2^ receptor subtype, has been suggested to be involved in learning and memory processing. However, the precise role of Y^sub 2^ receptors in learning and memmory remains unclear. In the present study, mice lacking NPY Y^sub 2^-type receptors were assessed in two animal models of learning and memory processing. We found that NPY Y ^sub 2^ ^sup -/-^ mice displayed a deficit on the probe trial in the Morris water maze task, whereas acquisition performance, swim speed, and visible platform performance did not differ significantly between groups. In addition, NPY Y ^sub 2^ ^sup -/-^ mice exhibited a marked deterioration in object memory 6 h, but not 1 h, following initial exposure in the object recognition test. Both groups of mice showed similar locomotor activity profiles in a low-stress, open field test. These data support the hypothesis that Y^sub 2^ receptors are involved in the regulation of learning and memory processing.[PUBLICATION ABSTRACT]