N-Ethylmaleimide-Sensitive Factor Deletion in Dopamine D2 Receptor Cells and Associated Neuronal and Behavioural Changes in Mice

N-ethylmaleimide-sensitive factor (NSF) plays a crucial role in neurotransmitter release and membrane molecule trafficking by regulating membrane fusion. Dysfunction of NSF has been linked to neuropsychiatric disorders. Although the interaction of NSF with dopamine receptor 2 (D2R) and the resulting excitotoxicity from its reduction in vitro have been demonstrated, the role of NSF in D2R-expressing cells in vivo remains unclear. This study investigated the effects of NSF loss on the survival of D2R-expressing cells and on mouse behaviour. We generated D2R-specific NSF conditional knockout (Nsff/f;D2R-Cre) mice. Targeted deletion of NSF in D2R-expressing cells led to a significant decrease in D2R-expressing neurons, accompanied by increased apoptosis during postnatal development, reduced striatal volume, and substantially lowered dopamine levels in the striatum. Further evidence of dopaminergic dysfunction was shown by reduced dopamine transporter expression in the striatum and tyrosine hydroxylase expression in the striatum and substantia nigra. The Nsff/f;D2R-Cre mice exhibited attention deficit hyperactivity disorder (ADHD)-like behaviours, including hyperactivity and impulsivity. Notably, combined administration of methylphenidate and a D2R agonist effectively alleviated hyperactivity and impulsivity, indicating a potential synergistic approach for ADHD treatment. These findings highlight the critical role of NSF in the survival of D2R-expressing neurons and suggest that disruption of the NSF-D2R interaction may contribute to ADHD-like phenotypes. This study underscores the translational relevance of the Nsff/f;D2R-Cre model for ADHD and suggests that targeting D2R dysfunction, particularly in treatment-resistant cases, may represent a promising therapeutic strategy for ADHD.