Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin 300052, China; Tianjin Research Institute of Anesthesiology, Tianjin 300052, China.
Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin 300052, China; Tianjin Research Institute of Anesthesiology, Tianjin 300052, China.
Neurosci Lett. 2020 Nov 20;739:135429. doi: 10.1016/j.neulet.2020.135429. Epub 2020 Oct 16.
Bone fracture may subsequently cause chronic postoperative pain after orthopedic surgery, but mechanisms remain elusive. The necessity of caspase-3 in neuroinflammation and synaptic plasticity has been summarized in pathological pain. Leucine-rich repeat transmembrane protein 1 (LRRTM1) mediates synaptic delivery of AMPA receptor and synaptogenesis. This study evaluated whether caspase-3 and LRRTM1 are required for fracture-associated postoperative allodynia.
A model of tibial fracture with intramedullary pinning in mice was established for the induction of postoperative pain, verified by measurement of mechanical paw withdrawal threshold and cold scores response to acetone. The caspase-3 specific inhibitor, recombinant caspase-3 and LRRTM1 knockdown by shRNA were utilized for the investigation of pathogenesis as well as the prevention of allodynia. Also, the activity of caspase-3 and the expression of LRRTM1 in the spinal dorsal horn were examined by Western blot and RT-qPCR.
This study reported that tibial fracture and orthopedic surgery produced long-lasting mechanical allodynia and cold allodynia, along with the up-modulation of spinal caspase-3 activity (but not caspase-3 expression) and LRRTM1 expression. Spinal caspase-3 inhibition prevented fracture-associated behavioral allodynia in a dose-dependent manner. Caspase-3 inhibitor also reduced the spinal increased LRRTM1 level after tibial fracture with pinning. Spinal LRRTM1 deficiency impaired fracture-caused postoperative pain. Intrathecal recombinant caspase-3 facilitated acute pain hypersensitivity and spinal LRRTM1 expression in naïve mice, reversing by LRRTM1 knockdown.
Our current results demonstrate the spinal up-regulation of LRRTM1 by caspase-3 activation in the development of tibial fracture-associated postoperative pain in mice.
骨科手术后，骨折可能随后导致慢性术后疼痛，但机制仍不清楚。半胱天冬酶-3 在神经炎症和突触可塑性中的必要性在病理性疼痛中已有总结。亮氨酸丰富重复跨膜蛋白 1（LRRTM1）介导 AMPA 受体的突触传递和突触发生。本研究评估了 caspase-3 和 LRRTM1 是否是骨折相关术后痛觉过敏所必需的。
建立了一种小鼠胫骨骨折伴髓内钉固定的模型，以诱导术后疼痛，通过测量机械性足底撤回阈值和丙酮引起的冷评分来验证。使用半胱天冬酶-3 特异性抑制剂、重组半胱天冬酶-3 和 shRNA 敲低 LRRTM1 来研究发病机制以及预防痛觉过敏。还通过 Western blot 和 RT-qPCR 检测脊髓背角中 caspase-3 的活性和 LRRTM1 的表达。
本研究报道胫骨骨折和骨科手术产生了持久的机械性痛觉过敏和冷觉过敏，同时脊髓 caspase-3 活性（而非 caspase-3 表达）和 LRRTM1 表达上调。脊髓 caspase-3 抑制以剂量依赖的方式预防与骨折相关的行为性痛觉过敏。Caspase-3 抑制剂还降低了胫骨骨折伴钉固定后脊髓中升高的 LRRTM1 水平。脊髓 LRRTM1 缺陷损害了骨折引起的术后疼痛。鞘内重组 caspase-3 促进了鞘内注射重组 caspase-3 对急性疼痛过敏的敏感性和脊髓 LRRTM1 表达，LRRTM1 敲低逆转了这种作用。
我们目前的结果表明，在小鼠胫骨骨折相关术后疼痛的发展过程中，脊髓中 LRRTM1 的上调是由 caspase-3 激活引起的。
