Differential effects of the pharmacological stressor yohimbine on impulsive decision making and response inhibition.

M C Schippers,T Pattij,T J De Vries,D Schetters

doi:10.1007/s00213-016-4337-3

Abstract

RationaleHigh levels of impulsivity have been associated with psychiatric disorders such as attention-deficit/hyperactivity disorder (ADHD) and substance abuse. In addition, acute stress is known to exacerbate many psychiatric symptoms in impulse control disorders.ObjectivesThe purpose of the current study was to investigate the acute effects of the pharmacological stressor yohimbine on response inhibition and impulsive choice.MethodsA group of male rats (n = 12) was trained in the delayed reward task (DRT) to assess impulsive choice. A separate group (n = 10) was trained in the stop-signal task (SST) to measure response inhibition. Upon stable responding, the effects of yohimbine (0, 1.25, 2.5, and 5 mg/kg i.p.) were tested in a Latin square design.ResultsAcute yohimbine significantly increased the preference for the large and delayed reinforcer in the DRT, indicating a decrease in impulsive choice. On the contrary, the effect size of 1.25 mg/kg yohimbine on stop-signal reaction times correlated negatively with baseline performance, suggesting a baseline-dependent effect on response inhibition as measured in the SST.ConclusionsThe current data suggest that the effects of the pharmacological stressor yohimbine on impulse control strongly depend on the type of impulsive behavior. Pharmacological stress decreased impulsive decision making, an observation that is in line with previously published rodent studies. By contrast, the lowest dose of yohimbine revealed a baseline-dependent effect on response inhibition. As such, the effects of yohimbine are largely comparable to the effects of psychostimulants on impulsivity and may support the notion of cross sensitization of stress and psychostimulants.

Highlights

Maladaptive impulsive behavior is associated with many psychiatric disorders, such as drug addiction, obsessivecompulsive disorder, attention-deficit/hyperactivity disorder (ADHD), bipolar disorder, and pathological gambling (Fineberg et al 2014; Moeller et al 2001; Pattij and De Vries 2013)
Further post hoc pairwise comparisons revealed that all three doses of yohimbine significantly increased preference for the large reward compared to the vehicle condition
The response latencies to start a trial were significantly altered by yohimbine administration [F(3,33) = 12.60, p < 0.001], and further post hoc analyses revealed a significant increased latency by the highest dose of 5 mg/kg compared to all other doses (p < 0.05; Table 2)

Summary

Introduction

Maladaptive impulsive behavior is associated with many psychiatric disorders, such as drug addiction, obsessivecompulsive disorder, attention-deficit/hyperactivity disorder (ADHD), bipolar disorder, and pathological gambling (Fineberg et al 2014; Moeller et al 2001; Pattij and De Vries 2013). Impulsivity is a multifaceted concept (Evenden 1999), and it has been recognized that different forms of impulsive behavior can be dissociated on a neuroanatomical, neuropharmacological, and behavioral level (Evenden 1999; Pattij and Vanderschuren 2008) In this regard, two main forms of impulsive behavior have been recognized, namely, impulsive action and impulsive choice, which do not correlate on the individual level, suggesting distinct underlying neural mechanisms (Broos et al 2012; Robinson et al 2009; Solanto et al 2001). Two main forms of impulsive behavior have been recognized, namely, impulsive action and impulsive choice, which do not correlate on the individual level, suggesting distinct underlying neural mechanisms (Broos et al 2012; Robinson et al 2009; Solanto et al 2001) Of these, the former can be defined as difficulties to inhibit either inappropriate or planned motor responses. The latter, impulsive choice is defined as the preference for a small

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