Citalopram elicits a discriminative stimulus in rats at a dose selectivelyincreasing extracellular levels of serotonin vs. dopamine and noradrenaline

Citalopram (2.5 mg/kg, i.p.) increased (+145-+180%) extracellular levels of serotonin (5-hydroxytryptamine, 5-HT) in the frontal cortex, nucleus accum bens and striatum of freely-moving rats, whereas dopamine and noradrenaline were unaffected. At this dose, employing a two-lever, food-reinforced, dru g discrimination procedure, citalopram generated reliable recognition and f ully (> 80%) generalized to itself with an Effective Dose(50) (ED50) of 0.1 mg/kg, s.c. Two further selective 5-HT reuptake inhibitors, sertraline and paroxetine, fully generalized with ED(50)s of 0.01 and 0.04 mg/kg, s.c., r espectively. In contrast, the anxiolytic, diazepam (0.63), and the antipsyc hotic, clozapine (2.5), did not (less than or equal to 20%) generalize. In conclusion, the selective 5-HT reuptake inhibitor, citalopram, elicits a ph armacologically-specific discriminative stimulus in rats at a dose selectiv ely elevating extracellular concentrations of 5-HT. (C) 1999 Elsevier Scien ce B.V. All rights reserved.