Besides physical insult,
spinal cord injury (SCI) can also result from transient
ischemia, such as
ischemia-reperfusion SCI (I/R SCI) as a postoperative complication. Increasing evidence has suggested that oxidative stress and related reactive
aldehyde species are key contributors to cellular injury after SCI. Previous work in
spinal cord contusion injury has demonstrated that
acrolein, both a key product and an instigator of oxidative stress, contributes to post-traumatic
hyperalgesia. It has been shown that
acrolein is involved in post-SCI
hyperalgesia through elevated activation, upregulating, and sensitizing transient receptor potential
ankyrin 1 (TRPA1) in sensory neurons in dorsal root ganglia. In the current study, we have provided evidence that
acrolein likely plays a similar role in
hypersensitivity following I/R SCI. Specifically, we have documented a post-I/R SCI
hypersensitivity, with parallel elevation of
acrolein locally (spinal cord tissue) and systemically (urine), which was also accompanied by augmented TRPA1
mRNA in DRGs. Interestingly, known
aldehyde scavenger
phenelzine can significantly alleviate post-I/R SCI
hypersensitivity, reduce
acrolein, suppress TPRA1 upregulation, and improve motor neuron survival. Taken together, these results support the causal role of
acrolein in inducing
hyperalgesia after I/R SCI via activation and upregulation of TRPA1 channels. Furthermore, endogenously produced
acrolein resulting from metabolic abnormality in the absence of mechanical insults appears to be capable of heightening
pain sensitivity after SCI. Our data also further supports the notion of
acrolein scavenging as an effective
analgesic as well neuroprotective strategy in conditions where oxidative stress and
aldehyde toxicity is implicated.