Lack of effect of the 5-HT1A receptor antagonist WAY-100635 on murine agonistic behaviour

The present study examined the influences of the selective 5-HT1A receptor antagonist, WAY-100635, on the social and agonistic behavior exhibited by m ale resident mice during encounters with unfamiliar intruder conspecifics. Acute administration of WAY 100635 (0.01-1.0 mg/kg sc) dose dependently enh anced the duration of resident maintenance behavior, reaching statistical s ignificance at 1.0 mg/kg. The duration of resident attend/approach behavior was reduced at 0.01 mg/kg. Drug-free intruder animals showed a reduction i n the frequency and duration of attend/approach behavior when the resident mice were treated with 0.01 mg/kg WAY-100635. No other significant effects on behavior were detected for WAY 100635. A previous investigation reported that WAY-100635 induced anxiolytic-like effects in the mouse light/dark bo x test. In the present study, however, the level of defensive behavior of t he saline-treated resident mice was too low for any further anxiolytic-like attenuation of this behavior to be observed,. Therefore, no conclusions re garding the potential anxiolytic activity of WAY 100635 may be drawn from t he data presented here. Current results are consistent with data for the la ck of effect of WAY 100635 on rat agonistic behavior but contrast with find ings for the effects of the 5-HT1A receptor antagonists (+)-WAY-100135 and SDZ 216-525 on mouse agonistic behavior. (C) 1999 Elsevier Science Inc.