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.