Dopamine-Driven Neural Mechanisms Linked to Behavioral Addiction in Mouse Study

Researchers at Kanazawa University have identified how dopamine signaling in the medial nucleus accumbens (mNAc) regulates motivation in a mouse model of behavioral addiction, according to a study published in Neuropsychopharmacology. The findings, led by Assistant Professor Naoya Nishitani and Professor Katsuyuki Kaneda, reveal distinct roles for D1 and D2 dopamine receptors in reward seeking and consumption, offering new insights into potential treatments for addiction and psychiatric disorders.

How Dopamine Shapes Motivation in Behavioral Addiction

The study focused on the mNAc, a brain region critical for reward processing, and its interaction with dopamine receptors. Using a novel operant task where mice earned wheel-running rewards through nose-poke actions, researchers observed that dopamine release increased before reward seeking and again after reward consumption. This pattern was disrupted by D1 receptor antagonists, which blocked the reduction in mNAc neural activity during reward seeking.

“Dopamine release appears to drive motivation by modulating neural activity in the mNAc,” said Nishitani. “Our results highlight the specific roles of D1 and D2 receptors in separating reward seeking from consumption, which could explain why some individuals develop compulsive behaviors.”

Implications for Understanding Behavioral Addictions

Behavioral addictions, such as excessive internet use or gambling, have gained attention as societal concerns. However, creating animal models for these behaviors has been challenging. The study’s use of wheel running—a natural reward for mice—provides a framework for studying compulsive reward-seeking behaviors. Previous research has shown that wheel running shares neural and behavioral similarities with drug addiction, making it a valuable model.

“This model allows us to dissect the neural circuits underlying abnormal motivation,” Kaneda explained. “By targeting dopamine receptors, we may develop therapies for conditions where reward processing is dysregulated, such as depression or addiction.”

Methodology and Key Findings

The researchers used fiber photometry to monitor real-time dopamine release and neural activity in the mNAc. Mice required 10 nose pokes to access 1 minute of wheel running, with nose pokes measuring reward seeking and running duration reflecting reward consumption. Pharmacological experiments revealed that D1 receptors were essential for both processes, while D2 receptors primarily influenced reward seeking.

“The separation of reward seeking and consumption into distinct neural pathways suggests that treatments could be tailored to specific symptoms,” noted the study. For example, D1 antagonists might reduce excessive reward seeking, while D2 modulators could address compulsive consumption.

Future Directions and Clinical Relevance

The study underscores the importance of dopamine signaling in motivation and highlights the mNAc as a target for therapeutic interventions. Future research may explore how these mechanisms apply to human disorders, such as major depressive disorder, where altered reward processing is a hallmark.

“Understanding these circuits could lead to more precise treatments,” said Nishitani. “Our work provides a foundation for investigating how dopamine dysregulation contributes to psychiatric conditions.”

Publication details: Naoya Nishitani et al, “Medial nucleus accumbens dopamine receptors modulate motivation for wheel running in male mice,” Neuropsychopharmacology (2025).