Negative urgency is a facet of impulsivity that reflects mood-based rash action and is associated with various maladaptive behaviors in humans. However, the underlying neural mechanisms of negative urgency are not fully understood. Several brain regions within the mesocorticolimbic pathway, as well as the neurotransmitters dopamine (DA) and serotonin (5-HT), have been implicated in impulsivity. Extracellular DA and 5-HT concentrations are regulated by DA transporters (DAT) and 5-HT transporters (SERT); thus, these transporters may be important molecular mechanisms underlying individual differences in negative urgency. The current study employed a reward omission task to model negative urgency in rats. During reward trials, a cue light signaled the non-contingent delivery of one sucrose pellet; immediately following the non-contingent reward, rats responded on a lever to earn sucrose pellets (operant phase). Omission trials were similar to reward trials, except that non-contingent sucrose was omitted following the cue light prior to the operant phase. As expected, contingent responding was higher following omission of expected reward than following delivery of expected reward, thus reflecting negative urgency. Upon completion of behavioral training, Vmax and Km were obtained from kinetic analysis of [3H]DA and [3H]5-HT uptake using synaptosomes prepared from nucleus accumbens (NAc), dorsal striatum (Str), medial prefrontal cortex (mPFC), and orbitofrontal cortex (OFC) isolated from individual rats. Vmax for DAT in NAc and for SERT in OFC were positively correlated with negative urgency scores. The current findings suggest that mood-based impulsivity (negative urgency) is associated with enhanced DAT function in NAc and SERT function in OFC.
|Number of pages||8|
|Journal||Behavioural Brain Research|
|State||Published - Sep 5 2015|
Bibliographical noteFunding Information:
This work was supported by National Institutes of Health grants P50 DA05312 , R01 DA12964 , UL1 TR000117 , and T32 DA016176 . The authors would like to thank Emily Denehy and Travis McCuddy for technical assistance.
© 2015 Elsevier B.V.
- Dopamine transporter
- Negative urgency
- Nucleus accumbens
- Orbitofrontal cortex
- Serotonin transporter
ASJC Scopus subject areas
- Behavioral Neuroscience