Effects of atomoxetine, desipramine, D-amphetamine and methylphenidate on impulsivity in juvenile rats, measured in a T-maze procedure

Impulsivity is a core symptom of Attention Deficit/Hyperactivity Disorder (ADHD). In the present study, we assessed the effects of two stimulants, methylphenidate and D-amphetamine and of two non stimulant noradrenaline reuptake inhibitors, atomoxetine and desipramine, on the tolerance to delay of reward, taken as an index of impulsivity, in juvenile Wistar rats. Animals were trained in a T-maze to choose between a small-and-immediate reward and a large-but-30 s-delayed reward. The effects of drugs were studied on the performance of animals at 30-40 day of age. Methylphenidate (3 mg/kg), atomoxetine (1 mg/kg), D-amphetamine (1 and 2 mg/kg) and desipramine (8 and 16 mg/kg) increased the number of choices of the large-but-delayed reward, i.e. decreased impulsivity. Given that these drugs are commonly prescribed in ADHD, these data indicate that the T-maze procedure in juvenile animals may be suitable for testing the therapeutic potential of drugs intended to the treatment of ADHD in children. (C) 2010 Elsevier Ireland Ltd. All rights reserved.