Preoperative sleep deprivation prolongs postoperative hyperalgesia by downregulating spinal cord D2R expression via the PP2A/AKT-dependent NMDA receptor phosphorylation.

Preoperative sleep deprivation (SD) is known to exacerbate postoperative pain, but the underlying mechanisms remain unclear. Using a male mouse model of 48-h continuous SD followed by incisional surgery, we found that SD alone induced transient mechanical hyperalgesia, and when combined with surgery (SI group) it significantly aggravated and prolonged postoperative pain recovery until day 10. On postoperative day 7, SI mice showed marked downregulation of spinal dopamine D2 receptor (D2R) expression and decreased spinal dopamine concentration. D2R was predominantly expressed on spinal glutamatergic neurons. Overexpression of D2R on these neurons via intrathecal AAV injection effectively alleviated the prolonged hyperalgesia, normalizing pain sensitivity by day 7. Mechanistically, D2R downregulation led to increased phosphorylation of NMDA receptor subunits (p-NR1 and p-NR2B) without altering total NMDA receptor levels. Co-immunoprecipitation revealed an interaction between D2R and protein phosphatase 2A (PP2A). SI mice exhibited decreased PP2A expression but increased p-AKT, p-GSK3β, and β-catenin, indicating activation of the PP2A/AKT signaling pathway, which were reversed by D2R overexpression. Furthermore, pharmacological activation of PP2A with DT-061 not only downregulated p-AKT, p-GSK3β, β-catenin, p-NR1 and p-NR2B, but also produced significant analgesia in SI mice. Collectively, these results demonstrate that preoperative sleep deprivation prolongs postoperative hyperalgesia by downregulating spinal D2R on glutamatergic neurons, which disinhibits the PP2A/AKT pathway and enhances NMDA receptor phosphorylation. Targeting D2R or its downstream PP2A/AKT signaling may represent a novel therapeutic strategy for managing persistent postoperative pain caused by preoperative sleep deprivation in male mice.