Effects of cortical and striatal dopamine D1 receptor blockade on cued versus noncued behavioral responses
Won Yung Choi1, Cecile Morvan Campbell, Peter D Balsam
1Department of Psychiatry, Columbia University, NY, USA.
Abstract:
Various lines of evidence suggest that disruptions in brain dopamine (DA) transmission produce behavioral impairments that can be overcome by salient response-eliciting environmental stimuli. We examined here whether D1 receptor blockade within striatal or frontal cortical DA target regions would differentially affect head entry responses elicited by an auditory cue compared with those occurring during noncued intertrial intervals. Rats received 2 drug-free 28-trial daily sessions in which an auditory cue was immediately followed by food delivery. On the following day, separate groups of rats received bilateral infusions of D1 antagonist SCH23390 to the dorsomedial striatum (DMS), nucleus accumbens (NAcc) core, or the medial prefrontal cortex (mPFC). SCH23390 infused into the DMS and NAcc core suppressed noncued head entries but had no effect on head entries in response to the auditory cue. SCH23390 infused to the mPFC did not reduce either cued or noncued approach responses. Systemic administration of the drug, in contrast, reduced the frequency of both cued and noncued approaches. The results are consistent with the notion that has emerged from the Parkinson's literature that reduced DA transmission produces behavioral suppression that can be overcome by salient environmental response elicitors, and extends this notion by showing that D1 receptor transmission within the striatum strongly suppresses noncued responses while leaving the identical behavior intact when cued by an environmental stimulus.
Insights
Dopamine (DA) D1 receptor blockade in the striatum suppresses non-cued behaviors but spares cue-elicited responses. This suggests environmental cues can overcome dopamine deficits, offering insights into Parkinson's disease and behavioral control.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Pharmacology
Background:
- Disruptions in dopamine (DA) transmission are linked to behavioral impairments.
- Salient environmental stimuli can overcome these deficits.
- The role of specific dopamine receptor subtypes and brain regions in this phenomenon requires further elucidation.
Purpose of the Study:
- To investigate the differential effects of D1 receptor blockade in striatal and frontal cortical regions on cue-elicited versus non-cued behaviors.
- To determine if D1 receptor antagonism in the dorsomedial striatum (DMS), nucleus accumbens (NAcc) core, or medial prefrontal cortex (mPFC) affects head entry responses.
- To compare the effects of local D1 blockade with systemic administration of a D1 antagonist.
Main Methods:
- Rats were trained to associate an auditory cue with food delivery.
- Bilateral infusions of the D1 antagonist SCH23390 were administered to the DMS, NAcc core, or mPFC.
- Head entry responses were measured during cued trials and non-cued intertrial intervals.
- Systemic administration of SCH23390 was also performed for comparison.
Main Results:
- D1 receptor blockade in the DMS and NAcc core suppressed non-cued head entries but did not affect cue-elicited head entries.
- D1 receptor blockade in the mPFC did not significantly alter either cued or non-cued responses.
- Systemic administration of SCH23390 reduced both cued and non-cued approach behaviors.
Conclusions:
- D1 receptor transmission within the striatum plays a critical role in suppressing non-cued behaviors.
- Environmental cues can effectively overcome D1 receptor-mediated behavioral suppression in the striatum.
- These findings extend the understanding of dopamine's role in behavioral control, particularly in the context of Parkinson's disease, highlighting the potential for salient stimuli to modulate behavior despite dopamine deficits.
