Divergent Dopamine–Acetylcholine Adaptations During Psychostimulant Sensitization

Lange G, Gnazzo F, Faust RP, Beeler JA. Accumbal dopamine and acetylcholine dynamics during psychostimulant sensitization. bioRxiv [Preprint]. 2025;2025.03.29.646091. doi: 10.1101/2025.03.29.646091.

Background: Behavioral sensitization to repeated psychostimulant exposure reflects neural adaptations implicated in addiction. Dopamine (DA) signaling in the nucleus accumbens (NAcc) is central to this process, but striatal acetylcholine (ACh), released by cholinergic interneurons (CINs), may also contribute through reciprocal interactions with DA. However, how psychostimulants alter ACh dynamics and DA–ACh coupling across repeated exposures has not been fully characterized.

Hypothesis: This study hypothesized that repeated psychostimulant exposure would differentially alter dopamine and acetylcholine signaling in the NAcc, producing sensitized changes dependent on dopamine D2 receptors expressed on cholinergic interneurons.

Methods: The authors used dual-color fiber photometry (GRAB-rDA and GRAB-ACh sensors; FP3002) to record simultaneous DA and ACh activity in the NAcc shell of freely moving mice. Animals received repeated injections of cocaine, amphetamine or saline, followed by a drug-challenge session; a separate cohort of CIN-specific D2R knockout mice underwent the same protocol.

Results: Repeated psychostimulant exposure enhanced locomotor activity and produced sensitized increases in slow extracellular DA while reducing the amplitude and frequency of phasic DA transients. ACh transients were suppressed in amplitude and frequency, effects that sensitized across sessions. Psychostimulants weakened DA–ACh correlations and coherence without altering their temporal alignment. CIN-specific D2R knockout mice displayed delayed behavioral sensitization and failed to show DA or ACh sensitization despite preserved acute responses.

Conclusions: Repeated psychostimulant exposure induces sensitized, opposing adaptations in NAcc dopamine and acetylcholine signaling. D2 receptors on cholinergic interneurons are essential for neuromodulator sensitization but not for the expression of behavioral sensitization itself.