Background and objectives: Recent studies have suggested that nuclear factor κB (NF-κB) may play a role in mediating nerve injury-induced neuropathic pain. Here, we examined the effects of intrathecal pyrrolidine dithiocarbamate (PDTC), a NF-κB inhibitor, on the development of neuropathic pain, spinal microglial activation, and CX3CR1 expression induced by sciatic chronic constriction injury (CCI) model in rats.
Methods: Under chloral hydrate anesthesia, male Sprague-Dawley rats (300-350 g) fitted with intrathecal catheters underwent either sciatic CCI or sham surgery. Intrathecal saline or PDTC (100 or 1000 pmol/d) was infused 1 day before or 3 days after CCI (n = 8). The rat hind-paw withdrawal threshold to mechanical stimuli and withdrawal latency to radiant heat were determined before surgery and from days 1 to 7 after CCI. Spinal microglial activation was evaluated with OX-42 immunoreactivity, and spinal CX3CR1 expression was assessed by Western blotting.
Results: Chronic constriction injury induced mechanical allodynia and thermal hyperalgesia and microglial activation as demonstrated by OX-42 expression. Whereas it had no apparent effect on spinal cord histology, intrathecal administration of PDTC prevented the development of the mechanical and thermal hyperalgesia and inhibited nerve injury-induced microglial activation and spinal CX3CR1 expression.
Conclusions: In this study, we have shown the protective effect of intrathecal PDTC on the development of nociceptive behaviors induced by CCI in rats. The activation of NF-κB pathway may contribute to spinal microglial activation and CX3CR1 up-regulation.