the effect of acute lithium and ami-193, a new 5ht2 antagonist, on apomorphine-induced pecking in pigeon

intramascular (im) administration of apomorphine (a mixed d1/d2 dopamine receptors agonist 0.2-1.6 mg/kg) induced pecking, a stereotype behavior in pigeons in a dose- dependent manner. in this study the effect of lithium (li+, 240 mg/kg, im) and ami-193 (a new 5-ht2 antagonist, 0.003 mg/pigeon) on apomorphine-induced peking (aip) were investigated. this study showed that li+ and ami-193 did not induce pecking by itself but administration of each of these agents before apomorphine increased and decreased the aip (apomor-phine 0.8 mg/kg) respectively whereas concomitant use of li+ (240 mg/kg im) and ami-193 decreased aip significantly. these results suggested that 5-ht2 antagonists inhibit the inhibitory effect of serotonin on the dopamine release in the raphe-striatal pathway but li+ can modulate dopamine and serotonin function by different mechanisms and decrease this effect. as a result, it is mechanisms and decrease this effect. as a result, it is concluded serotonin can decrease the aip through 5-ht2 receptors indirectly by decrease the dopamine release.