Division of Neuroscience, Dept. of Oral and Maxillofacial Surgery, Box 100416, JHMHC, University of Florida College of Dentistry, Gainesville, FL 32610, USA.
Toxicol Appl Pharmacol. 2022 Jan 1;434:115821. doi: 10.1016/j.taap.2021.115821. Epub 2021 Dec 9.
We examined whether combinations of K7 channel openers could be effective modifiers of deep tissue nociceptor activity; and whether such combinations could then be optimized for use as safe analgesics for pain-like signs that developed in a rat model of GWI (Gulf War Illness) pain. Voltage clamp experiments were performed on subclassified nociceptors isolated from rat DRG (dorsal root ganglion). A stepped voltage protocol was applied (-55 to -40 mV; V = -60 mV; 1500 ms) and K7 evoked currents were subsequently isolated by linopirdine subtraction. Directly activated and voltage activated K currents were characterized in the presence and absence of Retigabine (5-100 μM) and/or Diclofenac (50-140 μM). Retigabine produced substantial voltage dependent effects and a maximal sustained current of 1.14 pA/pF ± 0.15 (ED: 62.7 ± 3.18 μM). Diclofenac produced weak voltage dependent effects but a similar maximum sustained current of 1.01 ± 0.26 pA/pF (ED: 93.2 ± 8.99 μM). Combinations of Retigabine and Diclofenac substantially amplified resting currents but had little effect on voltage dependence. Using a cholinergic challenge test (Oxotremorine, 10 μM) associated with our GWI rat model, combinations of Retigabine (5 uM) and Diclofenac (2.5, 20 and 50 μM) substantially reduced or totally abrogated action potential discharge to the cholinergic challenge. When combinations of Retigabine and Diclofenac were used to relieve pain-signs in our rat model of GWI, only those combinations associated with serious subacute side effects could relieve pain-like behaviors.
我们研究了 K7 通道开放剂的组合是否可以有效地调节深部组织伤害感受器的活性；以及这些组合是否可以被优化为用于海湾战争相关疾病（Gulf War Illness）疼痛模型中发展的疼痛样症状的安全镇痛剂。在从大鼠 DRG（背根神经节）分离的亚分类伤害感受器上进行电压钳实验。应用逐步电压方案（-55 至-40 mV；V=-60 mV；1500 ms），并用利诺吡啶（linopirdine）减去法随后分离 K7 诱发电流。在存在和不存在瑞替加滨（Retigabine，5-100 μM）和/或双氯芬酸（Diclofenac，50-140 μM）的情况下，对直接激活和电压激活的 K 电流进行了表征。瑞替加滨产生了显著的电压依赖性效应，最大持续电流为 1.14±0.15 pA/pF（ED：62.7±3.18 μM）。双氯芬酸产生较弱的电压依赖性效应，但最大持续电流相似，为 1.01±0.26 pA/pF（ED：93.2±8.99 μM）。瑞替加滨和双氯芬酸的组合大大放大了静息电流，但对电压依赖性几乎没有影响。使用与我们的 GWI 大鼠模型相关的胆碱能挑战测试（Oxotremorine，10 μM），瑞替加滨（5 μM）和双氯芬酸（2.5、20 和 50 μM）的组合大大减少或完全消除了对胆碱能挑战的动作电位放电。当瑞替加滨和双氯芬酸的组合用于缓解我们的 GWI 大鼠模型中的疼痛症状时，只有那些与严重亚急性副作用相关的组合才能缓解疼痛样行为。
