5-HT1A receptor agonist effects of BMY-14802 on serotonin release in dorsal raphe and hippocampus

BMY-14802 (BMS-181100; alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazine butanol monohydrochloride) is a sigma receptor antagonist with potential antipsychotic activity. BMY-14802 also binds to 5-HT1A receptors and is able to inhibit the firing of dorsal raphe serotonergic neurons, suggesting that this compound has 5-HT1A receptor agonist properties in vivo. In the present study, we used in vivo microdialysis to study the effects of BMY-14802 on extracellular serotonin (5-hydroxytryptamine), 5-hydroxyindole-3-acetic acid (5-HIAA) and homovanillic acid (HVA) in the dorsal raphe and ventral hippocampus in the awake rat. Systemic injections of 5-20 mg/kg BMY-14802 induced a simultaneous dose-dependent decrease in 5-HT and markedly increased the dopamine metabolite, HVA concentrations in dialysates from dorsal raphe and hippocampus. Extracellular concentrations of the 5-HT metabolite, 5-HIAA decreased only after 20 mg/kg BMY-14802. The 5-HT decreases in dorsal raphe and hippocampus produced by BMY-14802 were completely antagonized by pretreatment with 1.0 mg/kg of the specific 5-HT1A antagonist, WAY-100635 (N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl) cyclohexanecarboxamide trihydrochloride). These data indicate that BMY-14802 decreases dorsal raphe and hippocampal release of 5-HT by interaction with somatodendritic 5-HT1A receptors in the raphe nuclei and suggest that this compound is a potential anxiolytic.