Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226, USA.
Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226, USA.
Osteoarthritis Cartilage. 2022 Nov;30(11):1468-1481. doi: 10.1016/j.joca.2022.08.008. Epub 2022 Aug 24.
Chronic joint pain is common in patients with osteoarthritis (OA). Non-steroidal anti-inflammatory drugs and opioids are used to relieve OA pain, but they are often inadequately effective. Dorsal root ganglion field stimulation (GFS) is a clinically used neuromodulation approach, although it is not commonly employed for patients with OA pain. GFS showed analgesic effectiveness in our previous study using the monosodium iodoacetate (MIA) - induced OA rat pain model. This study was to evaluate the mechanism of GFS analgesia in this model.
After osteoarthritis was induced by intra-articular injection of MIA, pain behavioral tests were performed. Effects of GFS on the spontaneous activity (SA) were tested with in vivo single-unit recordings from teased fiber saphenous nerve, sural nerve, and dorsal root.
Two weeks after intra-articular MIA injection, rats developed pain-like behaviors. In vivo single unit recordings from bundles teased from the saphenous nerve and third lumbar (L3) dorsal root of MIA-OA rats showed a higher incidence of SA than those from saline-injected control rats. GFS at the L3 level blocked L3 dorsal root SA. MIA-OA reduced the punctate mechanical force threshold for inducing AP firing in bundles teased from the L4 dorsal root, which reversed to normal with GFS. After MIA-OA, there was increased retrograde SA (dorsal root reflex), which can be blocked by GFS.
These results indicate that GFS produces analgesia in MIA-OA rats at least in part by producing blockade of afferent inputs, possibly also by blocking efferent activity from the dorsal horn.
慢性关节疼痛在骨关节炎（OA）患者中很常见。非甾体抗炎药和阿片类药物用于缓解 OA 疼痛，但往往效果不佳。背根神经节场刺激（GFS）是一种临床应用的神经调节方法，尽管它通常不适用于 OA 疼痛患者。GFS 在我们之前使用单碘乙酸盐（MIA）诱导的 OA 大鼠疼痛模型的研究中显示出镇痛效果。本研究旨在评估 GFS 在该模型中的镇痛机制。
通过关节内注射 MIA 诱导 OA 后，进行疼痛行为测试。通过从 teased 纤维隐神经、腓肠神经和背根进行体内单细胞记录来测试 GFS 对自发性活动（SA）的影响。
在关节内注射 MIA 后 2 周，大鼠出现类似疼痛的行为。来自 MIA-OA 大鼠隐神经和第 3 腰椎（L3）背根 teased 束的体内单细胞记录显示 SA 的发生率高于来自生理盐水注射对照大鼠的发生率。L3 水平的 GFS 阻断了 L3 背根 SA。MIA-OA 降低了引发 AP 放电的点状机械力阈值，teased 从 L4 背根束中，GFS 使其恢复正常。在 MIA-OA 之后，逆行 SA（背根反射）增加，GFS 可以阻断逆行 SA。
这些结果表明，GFS 在 MIA-OA 大鼠中产生镇痛作用，至少部分是通过阻断传入输入产生的，也可能通过阻断背角的传出活动产生。
