Do antidepressants affect motivation in conditioned place preference?

The positive motivational effects of a range of antidepressants/neurotransmitter reuptake inhibitor compounds were studied using conditioned place preference. These agents included amitriptyline (2.5-10 mg/kg), venlafaxine (5 and 10 mg/kg), sibutramine (5 and 10 mg/kg), fluoxetine (2.5-10 mg/kg), paroxetine (5-15 mg/kg) and sertraline (2.5-10 mg/kg). Male Wistar rats were place conditioned in a three-compartment box to vehicle or drug alternately for 8 days using a 30-min pretreatment time. Control animals received vehicle only. Cocaine (5 mg/kg) was used as a positive control for the procedure. Significant place preference (P<0.05) was observed with paroxetine (15 mg/kg), fluoxetine (5 and 10 mg/kg), sertraline (2.5-10 mg/kg) and cocaine. Venlafaxine and sibutramine, serotonin/noradrenaline reuptake inhibitors, produced no place conditioning, while the highest dose of the tricyclic antidepressant, amitriptyline (10 mg/kg), produced signs of place aversion. The role of serotonin in reward pathways and differences in serotonin, noradrenaline and dopamine reuptake-inhibiting properties of these compounds may explain why only the serotonin-selective reuptake inhibitors produced place preference in this study.