Distinct Roles of Dopamine Receptor Subtypes in the Nucleus Accumbens during Itch Signal Processing

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Pharmacology

Background:

• Ventral tegmental area (VTA) dopaminergic neurons project to the nucleus accumbens (NAc) and are involved in reward and motivation.
• These VTA-NAc pathways have been implicated in itch processing, but the specific roles of dopamine receptor subtypes within NAc subregions remain unclear.

Purpose of the Study:

• To investigate the functional roles of dopamine D1 receptors (D1R) and D2 receptors (D2R) in the NAc shell subregions (lateral shell - LaSh, medial shell - MeSh) during itch processing.
• To elucidate the dynamics of dopamine release in the NAc during scratching behavior.

Main Methods:

• Pharmacological manipulation of D1R and D2R in the NAc shell of male mice.
• Assessment of pruritogen-induced scratching behavior.
• In vivo monitoring of dopamine release in the NAc using a dopamine sensor.

Main Results:

• Blockade of D1R in the NAc LaSh impaired scratching behavior.
• Activation of D2R in both NAc LaSh and MeSh attenuated scratching behavior.
• Dopamine release was elevated in the NAc LaSh at the onset of scratching and persisted even when itch-relief was blocked, suggesting a motivational role.

Conclusions:

• Dopamine D1R in the NAc lateral shell are crucial for motivating itch-induced scratching behavior.
• Dopamine D2R activation in the NAc shell can terminate scratching behavior.
• This study highlights the differential roles of dopamine receptor subtypes and dopamine signaling dynamics within NAc subregions in modulating itch perception and behavior.