Neuropeptide Y (NPY) Y2 receptors mediate behaviour in two animal models of anxiety:: evidence from Y2 receptor knockout mice

The behavioural phenotype of mice lacking neuropeptide Y (NPY) Y-2-type receptors was assessed in two well documented animal models of anxiety: namely, the elevated plus maze and the open field. NPY Y-2 -/- mice made more entries into, and spent significantly more time on, the open arms of the elevated plus maze when compared to their wild-type Y-2+/+ controls (P < 0.001). This effect was not due to non-specific changes in locomotor activity as the number of closed arm entries did not differ between groups. In addition, NPY Y-2-/- mice displayed increased preference for the central area of the open field when compared to Y-2+/+ animals (P < 0.01), whereas total entries did not differ between groups. This study suggests that NPY Y-2 receptors may play an inhibitory role and supports the hypothesis that Y-2 receptors are involved in the regulation of anxiety-like behaviours by NPY (C) 2002 Elsevier Science B.V. All rights reserved.