Impact of NPAS2 on mPFC dopamine synthesis and nap behavior.

Guo, Lianxia; Cen, Haobin; Huang, Yuwei; Li, Zanjin; Zeng, Kengran; Wu, Zicong; Weng, Jiaxian; Guo, Xiaocao et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

The biological basis of the afternoon nap, a widespread yet poorly understood phenomenon, has remained elusive. Here we identify NPAS2, among core circadian regulators, as a sex-independent determinant of the nap behavior in mice. Specifically, medial prefrontal cortex (mPFC)-expressed NPAS2 orchestrates nap regulation through circadian modulation of local dopaminergic activity. We demonstrate that tyrosine hydroxylase-positive (TH<sup>+</sup>) neurons in mPFC exhibit time-of-day dependent wake-promoting activity, showing minimal excitation precisely during nap hours. Mechanistically, NPAS2 achieves this circadian suppression through a POU2F2-TH regulatory pathway: 1) transcriptional activation of the transcription repressor POU2F2, and 2) consequent downregulation of TH expression (a rate-limiting enzyme for dopamine synthesis) and dopamine production in mPFC TH<sup>+</sup> neurons. These findings establish an endogenous circadian mechanism where mPFC NPAS2 periodically inhibits wake-promoting dopaminergic activity to drive nap behavior, providing fundamental insights into the neural and molecular regulation of nap biology.