Chronic atomoxetine treatment during adolescence does not influence decision making on a rodent gambling task, but does modulate amphetamine's effect on impulsive action in adulthood
In addition to the symptoms of inattention, hyperactivity, and impulsivity, individuals with attention deficit hyperactivity disorder exhibit impaired performance on tests of real world cost/benefit decision making. Atomoxetine, a nonstimulant drug approved for the treatment of attention deficit hyperactivity disorder, is a selective norepinephrine reuptake inhibitor administered chronically during adolescence, a time during which the frontal brain regions necessary for executive function undergo extensive maturation. This treatment protocol can affect behavior well into adulthood, but whether it produces long term changes in complex decision making has not been investigated. Twenty four Long Evans rats were administered saline or 1.0 mg/kg atomoxetine daily from postnatal day 40 to 54. Two weeks after treatment, the adult rats were trained and assessed on the rodent gambling task, in which the animals chose from four options varying in reward, punishment, and uncertainty. Impulsive action was also measured by recording the number of premature responses made. Regardless of the treatment administered during adolescence, rats learned to favor the advantageous options characterized by small, low penalty rewards in lieu of the larger, higher penalty reward options. Rodent gambling task performance was then assessed following acute treatment with atomoxetine (0.1 1.0 mg/kg) and amphetamine (0.3 1.5 mg/kg) Across groups, the highest dose of atomoxetine impaired decision making and decreased premature responding at all doses tested. Amphetamine also impaired choice performance, but selectively increased impulsive action in rats that had previously received atomoxetine treatment during adolescence. These findings contribute to our understanding of the long term effects associated with chronic adolescent atomoxetine exposure and suggest that this treatment does not alter decision making under conditions of risk and uncertainty in adulthood.
Behavioural pharmacology