Behavioral and neurochemical effects of anpirtoline and citalopram in isolated and group housed mice

1. Acute effects of serotonergic drugs acting via different mechanisms were investigated by a social interaction test and subsequent determination of serotonin and dopamine metabolisms in mice housed in groups or isolated for G weeks. 2. A resident / intruder test was performed with anpirtoline (5-HT1B recept or agonist in rodents; 1 mg/kg), citalopram (SSRI; 0.5 mg/kg) and saline tr eatment before animals were decapitated and different brain regions were fr ozen for subsequent HPLC-analyses. 3. Behavioral investigations indicated a strong increase of aggressive beha vior after 6 weeks of isolation housing. Acute citalopram treatment did not influence behavioral parameters of isolated and group housed mice. In cont rast, anpirtoline antagonized isolation induced aggressive behavioral compo nents in a specific manner. 4. Analysis of dopamine and serotonin metabolism revealed that citalopram t reatment did not affect dopamine metabolism, but reduced serotonin metaboli sm in the striatum, hippocampus, cortex and midbrain independent of housing conditions. 5. In contrast, anpirtoline treatment increased dopamine metabolism in cort ex, striatum and midbrain as well as influenced serotonin metabolism in a s tructure- and state-specific manner. Whereas anpirtoline decreased serotoni n metabolism in the cortex, the midbrain and the hippocampus independent of housing conditions, in the striatum anpirtoline abolished the isolation in duced decrease of serotonin metabolism. 6. These results indicate that anpirtoline might induce antiaggressive effe cts via postsynaptic receptor- and structure- specific activation of seroto nergic but also dopaminergic processes, whereas structure independent incre ase of synaptic serotonin via citalopram was ineffective to reverse aggress ivity in isolated mice.