Effects of methylphenidate and atomoxetine on impulsivity and motor activity in preadolescent rats prenatally-treated with alcohol.

Prenatal alcohol treatment (PA) produces a decrease in dopaminergic neuron activity in the ventral tegmental area, an alteration that is alleviated with methylphenidate treatment. Evidence exists that PA also produces hyperactivity, inattention and enhanced impulsivity, behavioral alterations that have been related to dopaminergic and noradrenergic functions. The purpose of this work was to study the effects of methylphenidate and atomoxetine on impulsivity and motor activity in preadolescent male rats prenatally exposed to alcohol. Pregnant Wistar rats were exposed to either alcohol or an isocaloric solution from Days 8 to 20 of gestation. Starting at 24 postnatal days, male offspring were tested for motor activity and trained in a delay-discounting task for impulsivity assessment before, and during, treatment with either 3 mg/kg i.p. of methylphenidate, 2 mg/kg i.p. of atomoxetine, or saline i.p. The group prenatally exposed to alcohol showed higher motor activity and more frequent choices of immediate, but small, rewards than the control group; a finding indicative of higher impulsivity. Atomoxetine reduced both motor activity and impulsivity. In contrast, methylphenidate had only a mild effect on impulsivity. Results suggest an important participation of noradrenergic transmission in cognitive impulsivity and hyperactivity in preadolescent rats with previous alterations in these behaviors. Dopaminergic participation in these behaviors is partially supported by the present findings on the basis of the effects of methylphenidate.