SGK1-HDAC4-HMGB1 signaling pathway in the spinal cord dorsal horn participates in diabetic neuropathic pain.

PURPOSE: This study aimed to determine whether serum-and glucocorticoid-inducible kinase1 (SGK1) activation-dependent histone deacetylase 4 (HDAC4) phosphorylation, nucleocytoplasmic trafficking, and subsequent regulation of high-mobility group protein box 1 (HMGB1) expression are involved in type 2 diabetic neuropathic pain (DNP).

METHODS

The type 2 diabetic neuropathic pain model was established in rats by feeding them with a high-fat and high-sugar diet for 8 weeks and then fasting them for 12 h, followed by a single intraperitoneal injection of streptozotocin (STZ, 35 mg/kg). SGK1 was inhibited in the spinal cord by intrathecal administration of the SGK1 inhibitor GSK-650394.

RESULTS

The present study revealed that pSGK1/tSGK1 was persistently upregulated in the spinal cord of rats with type-2 DNP. The downregulation of pSGK1/tSGK1 through the intrathecal injection of the SGK1 inhibitor GSK-650394 significantly ameliorated the pain hypersensitivity, relieved the abnormal expression of pHDAC4/tHDAC4 and HMGB1, and affected HDAC4 nucleocytoplasmic trafficking in DNP rats.

CONCLUSION

Our data suggest that SGK1 in the spinal cord modulates type-2 DNP by regulating the HDAC4/HMGB1 pathway.