Spinal cord and peripheral nerve injury results in extensive damage to the locally injured cells as well as distant cells that are functionally connected to them. Both primary and secondary damage can cause a broad range of clinical abnormalities, including neuropathic pain and cognitive and memory dysfunction. However, the mechanisms underlying these abnormalities remain unclear, awaiting new methods to identify affected cells to enable examination of their molecular, cellular and physiological characteristics. Here, we report that both primary and secondary damage to cells in mouse models of spinal cord and peripheral nerve injury can be detected in vivo using a novel fluorescent reporter system based on the immediate stress response via activation of Heat Shock Factor 1. We also provide evidence for altered electrophysiological properties of reporter-positive secondarily-injured neurons. The comprehensive identification of injured, but surviving cells located both close and at distant locations from the injury site in vivo will provide a way to study their pathophysiology and possibly prevention of their further deterioration.
Keywords: Cellular damage; DRG, dorsal root ganglion; FG, Fluoro-Gold; HRP, horseradish peroxidase; HSE, heat shock-response element; HSF1, heat shock factor 1; HSP, heat shock protein; Heat shock signaling; IL-6, interleukin 6; M1, primary motor cortex; M2, secondary motor cortex; MPtA, medial parietal association cortex; PBS, phosphate buffered saline; PCR, polymerase chain reaction; RFP, red fluorescent protein; Reporter mouse; SCI, spinal cord injury; SNI, sciatic nerve injury; Sciatic nerve injury; Spinal cord injury; WDR, wide-dynamic range; WGA, wheat germ agglutinin.