Effects of Acute Stress on Motor and Cognitive Impulsivity
Mahoney, Megan Kelly
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Impulsivity and stress are two of the most important determinants of drug addiction in that both factors predict the initiation and maintenance of drug use, as well as relapse to drug taking following abstinence. Despite this combined influence, the interaction between stress and impulsivity has never been examined systematically in animal models of addiction. The objective of the current study is to examine the role of acute stress on two different measures of impulsivity in rats: the Go/No-go test measures motor impulsivity, and the Delayed Reinforcement Paradigm measures cognitive impulsivity. To determine whether a 1 hr restraint stress is physiologically stressful, blood samples from rats in Experiment 1 were taken at 5 different sampling points: baseline (0 min), reactivity (15 and 60 min) and recovery (100 and 180 min). In Experiments 2 and 3, rats were tested in either the Go/No-go test or the Delayed Reinforcement test immediately following 1 hr of restraint stress. Results from Experiment 1 show that 1 hr of restraint stress increased plasma corticosterone concentrations at 15 min and 60 min; corticosterone concentrations returned to baseline levels by 100 min. Following stress, the percentage of Go interval responding was not altered during Go/No-go testing (Experiment 2), nor were there changes in the indifference point values during Delayed Reinforcement testing (Experiment 3). These results suggest that 1 hr of acute stress does not increase either motor or cognitive impulsivity, and stress may influence addiction via mechanisms that are independent of impulsivity.