The effects of chronic stress both alone and in combination with the antidepressant, nefazodone, which possesses antagonistic activity at the 5-HT2A receptor, were examined on the 5-HT2A receptor-mediated behaviour, wet dog shaking and sexual behaviour. Ovariectomized female rats received either a chronic stressor or no stress for 30 days, and half of each group received concurrent nefazodone treatment (100 mg/kg/day). Following treatment with either estrogen, or estrogen combined with progesterone, sexual behaviour and wet dog shaking were recorded. Chronic stress alone was found to facilitate sexual behaviour and increase wet dog shaking, while nefazodone administration alone was without effect. Furthermore, nefazodone completely attenuated the stress-induced facilitation of wet dog shaking, but not sexual behaviour. (C) 1999 Elsevier Science B.V. All rights reserved.