Summary:
Researchers have demonstrated that deleting the membrane-fusion protein NSF specifically from dopamine D2 receptor (D2R)-expressing neurons leads to striatal shrinkage, severe dopamine depletion, and classic ADHD-like hyperactivity and impulsivity in mice. While the frontline ADHD drug methylphenidate failed alone, combining it with a D2R activator successfully reduced impulsive and hyperactive behaviors, offering potential therapeutic directions for treatment-resistant ADHD.
Key Facts:
- Cell Loss and Striatal Atrophy: Knocking out N-ethylmaleimide-sensitive factor (NSF) in D2R neurons triggered increased early developmental cell death, leading to significantly fewer D2R-expressing cells, lower dopamine concentrations, and a reduced striatum volume.
- Marked Behavioral Changes: The knockout mice exhibited prominent hyperactivity and heightened impulsivity; in a platform jumping task, 86% of the modified mice jumped off within seven minutes compared to only 31% of control animals.
- Synergistic Dual Treatment: Monotherapy with methylphenidate did not alleviate hyperactivity in the modified mice, but co-administering it with the D2R agonist quinpirole reduced jumping from 78% down to 11% while significantly curbing hyperactivity.
Source: University of Fukui
Attention-deficit/hyperactivity disorder (ADHD) is a widespread neurodevelopmental condition characterized by persistent patterns of inattention, hyperactivity, and impulsivity. Although clinical neuroscientists have long identified disruptions in the brain’s dopamine pathways as central to the disorder, the molecular mechanisms required to nurture, maintain, and protect dopamine-responsive neurons during early development have remained unclear.
This question is particularly critical in the striatum, a subcortical region that coordinates motor execution, reward processing, and executive behavioral control via dopamine D2 receptor (D2R)-expressing neurons.
To uncover the cellular machinery preserving these circuits, a research team from the University of Fukui examined the role of N-ethylmaleimide-sensitive factor (NSF)—a vital regulator of intracellular membrane fusion that coordinates neurotransmitter release and receptor trafficking.
“The motivation for this study came from previous findings suggesting that NSF may be involved in neurodevelopmental and neuropsychiatric disorders. NSF was known to interact with D2R; however, the role of this interaction in vivo remained unclear,” said lead investigator Min-Jue Xie, Ph.D., assistant professor at the University of Fukui’s Research Centre for Child Mental Development. “Because ADHD is thought to involve reduced striatal dopaminergic function and D2R dysfunction, we hypothesized that NSF may be important for maintaining D2R-expressing neurons and dopaminergic function.”
Molecular Loss Triggers Neurodevelopmental Deficits
Published in Neuropsychopharmacology, the researchers engineered conditional knockout mice lacking NSF exclusively within D2R-expressing cells.
The targeted deletion led to substantial neurodevelopmental damage. During early maturation, the absence of NSF caused elevated rates of programmed cell death, resulting in a marked deficit of D2R-expressing neurons and measurable atrophy of the striatum. Accompanying this structural decline was a sharp reduction in striatal dopamine concentrations, demonstrating that NSF plays a mandatory role in supporting the survival and functional signaling capacity of the striatal dopaminergic network.
These biological deficits translated into distinct behavioral shifts mirrored in clinical ADHD. The knockout animals exhibited elevated locomotor activity and pronounced impulsivity. When placed on an elevated platform during an impulse-control assessment, 86% of the NSF-deficient mice leapt off before the end of the seven-minute trial, compared to just 31% of wild-type control mice.
Overcoming Resistance to Standard Stimulants
The team subsequently tested how the animals’ behavioral symptoms responded to pharmacological interventions. Administering methylphenidate, one of the most widely prescribed first-line psychostimulant treatments for ADHD, failed to significantly suppress hyperactivity when delivered as a monotherapy.
However, rescue occurred when researchers added quinpirole, a selective D2R agonist, alongside methylphenidate. The combination treatment restored behavioral regulation, blunting hyperactivity and reducing impulsive jumping on the platform test from 78% down to 11%.
While the authors caution that animal models cannot immediately change clinical regimens, the synergistic response highlights a biological pathway for patients who fail to benefit from frontline stimulants alone.
“This is basic research and will not immediately lead to a new treatment,” Xie concluded. “However, it provides important clues for understanding how dopaminergic dysfunction may contribute to ADHD. In the future, these findings may help develop new therapeutic strategies targeting D2R function and striatal dopamine signaling, especially for treatment-resistant ADHD.”
Funding information
This work was supported, in part, by KAKENHI grants from the Ministry of Education, Culture, Sports, Science and Technology of Japan (16H05373 to H.M. for study design; 24K02131 to Y.F. for data analysis and 21K06752 to M.-J.X. for data collection and analysis). The decision to publish was also supported by internal funding from the University of Fukui. Open Access funding provided by University of Fukui.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this Genetics and Neurology Research:
- Media Contact: Yuuka Kawamoto
- Source: University of Fukui
- Image Credit: Image generated for Neuroscience News
- Original Research is Open Access: Neuropsychopharmacology (September 15, 2026). “Deletion of N-ethylmaleimide-sensitive factor in dopamine D2 receptor-expressing cells impairs striatal development and dopaminergic function and induces ADHD-like behaviors in mice” Authors: Min-Jue Xie, Koshi Murata, Hiroshi Kuniishi, Yugo Fukazawa, Noriyoshi Usui & Hideo Matsuzaki.
- DOI: 10.1038/s41386-026-02526-8
Abstract
Deletion of N-ethylmaleimide-sensitive factor in dopamine D2 receptor-expressing cells impairs striatal development and dopaminergic function and induces ADHD-like behaviors in mice
N-ethylmaleimide-sensitive factor (NSF) regulates membrane fusion, supporting neurotransmitter release and membrane protein trafficking. NSF dysfunction has been linked to neuropsychiatric disorders. Although NSF interacts with dopamine D2 receptor (D2R), and NSF reduction induces excitotoxicity in vitro, its role in D2R-expressing cells in vivo remains unclear.
This study examined the effects of NSF loss on D2R-expressing cell populations and mouse behaviors. We generated D2R-specific NSF conditional knockout (Nsf f/f;D2R-Cre) mice. Targeted NSF deletion in D2R-expressing cells reduced D2R expression and the density of D2R-expressing cells, together with their associated marker preproenkephalin. These changes were accompanied by increased apoptotic cell death during early postnatal development, reduced striatal volume, and markedly lower striatal dopamine levels.
Dopaminergic impairment was further indicated by reduced dopamine transporter expression in the striatum and reduced tyrosine hydroxylase expression in the striatum and substantia nigra. Nsf f/f;D2R-Cre mice exhibited attention-deficit/hyperactivity disorder (ADHD)-like behaviors, including hyperactivity and impulsivity. Combined administration of methylphenidate and a D2R agonist, quinpirole, alleviated both behaviors, suggesting a potential complementary approach for ADHD treatment.
These findings highlight the critical role of NSF in maintaining D2R-associated striatal neuronal populations and suggest that disruption of the NSF-D2R interaction may contribute to ADHD-like phenotypes. This study supports the translational relevance of the Nsf f/f;D2R-Cre model for ADHD and indicates that targeting D2R dysfunction, particularly in treatment-resistant ADHD, may be a promising therapeutic strategy.
