Kuthati Yaswanth, Rao Vaikar Navakanth, Huang Wei-Hsiu, Busa Prabhakar, Wong Chih-Shung
Department of Anesthesiology, Cathy General Hospital, Taipei 106, Taiwan.
PhD Program in Pharmacology and Toxicology, School of Medicine, Tzu Chi University, Hualien 970, Taiwan.
Antioxidants (Basel). 2023 Jul 24;12(7):1478. doi: 10.3390/antiox12071478.
Morphine (MOR) is a commonly prescribed drug for the treatment of moderate to severe diabetic neuropathic pain (DNP). However, long-term MOR treatment is limited by morphine analgesic tolerance (MAT). The activation of microglial cells and the release of glia-derived proinflammatory cytokines are known to play an important role in the development of MAT. In this study, we aimed to investigate the effects of the dipeptidyl peptidase-4 inhibitor (DPP-4i) teneligliptin (TEN) on MOR-induced microglial cell activation and MAT in DNP rats. DNP was induced in four groups of male Wistar rats through a single intraperitoneal injection of streptozotocin (STZ) (50 mg/kg, freshly dissolved in 5 mmol/L citrate buffer, pH 4.5). Sham rats were administered with the vehicle. Seven days after STZ injection, all rats were implanted with an intrathecal (i.t) catheter connected to a mini-osmotic pump, divided into five groups, and infused with the following combinations: sham + saline (1 µL/h, i.t), DNP + saline (1 µL/h, i.t), DNP + MOR (15 µg/h, i.t), DNP + TEN (2 µg/h, i.t), and DNP + MOR (15 µg/h, i.t) + TEN (2 µg/h, i.t) for 7 days at a rate of 1 μL/h. The MAT was confirmed through the measurement of mechanical paw withdrawal threshold and tail-flick tests. The mRNA expression of neuroprotective proteins nuclear factor erythroid 2-related factor (Nrf2) and heme oxygenase-1 (HO-1) in the dorsal horn was evaluated by quantitative PCR (qPCR). Microglial cell activation and mononucleate cell infiltration in the spinal cord dorsal horn were assessed by immunofluorescence assay (IFA) and Western blotting (WB). The results showed that co-infusion of TEN with MOR significantly attenuated MAT in DNP rats through the restoration of neuroprotective proteins Nrf2 and HO-1 and suppression of microglial cell activation in the dorsal horn. Though TEN at a dose of 2 μg has mild antinociceptive effects, it is highly effective in limiting MAT.
吗啡（MOR）是一种常用于治疗中度至重度糖尿病性神经病变性疼痛（DNP）的药物。然而，长期使用吗啡治疗受到吗啡镇痛耐受性（MAT）的限制。已知小胶质细胞的激活和胶质细胞衍生的促炎细胞因子的释放在MAT的发展中起重要作用。在本研究中，我们旨在研究二肽基肽酶-4抑制剂（DPP-4i）替奈利汀（TEN）对DNP大鼠中MOR诱导的小胶质细胞激活和MAT的影响。通过单次腹腔注射链脲佐菌素（STZ）（50mg/kg，新鲜溶解于5mmol/L柠檬酸盐缓冲液，pH 4.5）在四组雄性Wistar大鼠中诱导DNP。假手术大鼠给予赋形剂。STZ注射7天后，所有大鼠均植入与微型渗透泵相连的鞘内（i.t.）导管，分为五组，并以1μL/h的速率输注以下组合：假手术+生理盐水（1μL/h，i.t.）、DNP+生理盐水（1μL/h，i.t.）、DNP+MOR（15μg/h，i.t.）、DNP+TEN（2μg/h，i.t.）以及DNP+MOR（15μg/h，i.t.）+TEN（2μg/h，i.t.），持续7天。通过测量机械性缩爪阈值和甩尾试验来确认MAT。通过定量PCR（qPCR）评估背角中神经保护蛋白核因子红细胞2相关因子（Nrf2）和血红素加氧酶-1（HO-1）的mRNA表达。通过免疫荧光测定（IFA）和蛋白质免疫印迹（WB）评估脊髓背角中的小胶质细胞激活和单核细胞浸润。结果表明，TEN与MOR共同输注通过恢复神经保护蛋白Nrf2和HO-1以及抑制背角中的小胶质细胞激活，显著减轻了DNP大鼠的MAT。虽然剂量为2μg的TEN具有轻度的抗伤害感受作用，但它在限制MAT方面非常有效。
