• Yuecheng Lu, Baohua Lin, and Junmin Zhong.
• Department of Gynecology and Obstetrics, Guangzhou Women and Children's Medical Center, Guangzhou Medical University.
• Biol. Pharm. Bull. 2017 Sep 1; 40 (9): 1432-1438.

AbstractDiabetic neuropathy pain (DNP) is a common chronic complication of diabetes characterized by spontaneous pain, hyperalgesia and allodynia. Dexmedetomidine is a selective α2 adrenergic agonist that relieves sympathetic nervous tension and reduces the release of glutamate. Thus, it is possible that dexmedetomidine may relieve DNP as well. In this study, we examined the effect of dexmedetomidine on DNP in the presence or absence of the α2 adrenergic antagonist yohimbine in rats utilizing a streptozotocin (STZ)-induced diabetes as a model of DNP. To examine DNP, we examined behavior using the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) tests, and microglia and astrocyte activation was examined by immunofluorescence staining. The levels of pro-inflammatory cytokine tumor necrosis factor (TNF)-α and interleukin (IL)-1β in the spinal cord were measured by enzyme-linked immunosorbent assay (ELISA). Cell apoptosis in spinal cord was examined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assay. Glutamate production in caudal lumbar was measured by HPLC. We found that STZ-treated rats had decreased pain threshold, elevated activation of microglia but not astrocytes, increased level of pro-inflammatory cytokines, increased apoptosis and glutamate production compared to control animals, and these effects were ameliorated by dexmedetomidine treatment. Pretreatment of yohimbine abolished almost all of the protective effects of dexmedetomidine except for glutamate production.

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