Attention-deficit hyperactivity disorder (ADHD) is a highly heritable neurodevelopmental disorder that affects approximately 5.3% of children and approximately 2.5% of adults. There is an intimate relationship between ADHD and sleep disturbance. Specifically, individuals carry a mutation in the core circadian gene CRY1 (c. 1657 + 3A > C), which results in the deletion of exon 11 expression in the CRY1 protein (CRY1Δ11), causing them to exhibit typical ADHD symptoms. However, the underlying mechanism is still elusive. In this study, we demonstrate that Cry1Δ11 (c. 1717 + 3A > C) mice showed ADHD-like symptoms, including hyperactivity, impulsivity, and deficits in learning and memory. A hyperactive cAMP signaling pathway was found in the nucleus accumbens (NAc) of Cry1Δ11 mice. We further demonstrated that upregulated c-Fos was mainly localized in dopamine D1 receptor-expressing medium spiny neurons (DRD1-MSNs) in the NAc. Neuronal excitability of DRD1-MSNs in the NAc of Cry1Δ11 mice was significantly higher than that of WT controls. Mechanistically, the CRY1Δ11 protein, in contrast to the WT CRY1 protein, failed to interact with the Gαs protein and inhibit DRD1 signaling. Finally, the DRD1 antagonist SCH23390 normalized most ADHD-like symptoms in Cry1Δ11 mice. Thus, our results reveal hyperactive DRD1 signaling as an underlying mechanism and therapeutic target for ADHD induced by the highly prevalent CRY1Δ11 mutation.
Keywords: Neuroscience; Psychiatric diseases.