Estradiol and neuropeptide Y (intra-lateral septal) reduce anxiety-like behavior in two animal models of anxiety

Anxiolytic-like effects of intra-lateral septal nuclei (LSN) infusions of the neuropeptide Y(NPY) alone or combined with estradiol benzoate were assessed in ovariectomized Wistar rats in two animal models of anxiety-like behavior. In a conflict test, immediately punished responses were assessed: 17-beta-estradiol (50.0 mu g/rat, P < 0.05) plus vehicle (intra-LSN) or intra-LSN infusions of NPY (2.5 mu g/mu l, P < 0.05; 3.0 mu g/mu l, P < 0.05) plus vehicle (systemic route) or the combination of subthreshold doses of 17-beta-estradiol (25.0 mu g/kg) plus intra-LSN infusions of NPY (2.0 mu g/mu l, P < 0.05) increased the amount of immediately punished reinforcers. In the elevated plus-maze test several spatial-temporal variables were evaluated: 17-beta-estradiol (50.0 mu g/kg, P < 0.05) plus vehicle (intra-LSN) or intra-LSN infusions of NPY (2.5 mu g/mu l, P < 0.05; 3.0 mu g/mu l, P < 0.05) plus vehicle (systemic route) or the combination of subthreshold doses of 17-beta-estradiol (25.0 mu g/kg) plus intra-LSN infusions of NPY (2.0 mu g/mu l, P < 0.05) produced anxiolytic-like actions without affecting locomotion. It is concluded that estradiol or NPY may produce anxiolytic-like actions and that subthreshold doses of estradiol and subthreshold doses of NPY when combined produced anxiolytic-like actions. (c) 2008 Elsevier Inc. All rights reserved.