Sema3A relieves neuropathic pain by reducing eIF2α phosphorylation via suppressing PI3K/Akt/mTOR pathway

Primary sensory neurons serve as a critical link between the peripheral nervous system (PNS) and the central nervous system (CNS). They represent the initial neural tissue responsible for transmitting sensations and pain. In case where peripheral nerves are injured, nerve fiber regeneration can lead to severe pain. Semaphorin3A (Sema3A), an axon guidance molecule that can be secreted by Schwann cells, has been shown to effectively inhibit the regeneration of embryonic and adult dorsal root ganglion (DRG). However, its role in neuropathic pain and the underlying mechanisms remain unexplored. This study employed a chronic constriction injury (CCI) model of neuropathic pain in mice. We observed that increased expression of Sema3A could alleviate both mechanical and heat nociceptive behaviors in model mice. By overexpressing Sema3A in ipsilateral DRG neurons via DRG injection, we found that the phosphorylation of the PI3K/Akt/mTOR signaling pathway and eukaryotic initiation factor 2 alpha (eIF2 alpha) was inhibited, thereby inhibiting pain. eIF2 alpha is a translation initiation factor and its phosphorylation can regulate global translation. The inhibition of eIF2 alpha phosphorylation through PKR and PERK inhibitors also reduced the expression of ion channels and ultimately alleviated neuropathic pain. We found that Sema3A could suppress the phosphorylation of eIF2 alpha by inhibiting the PI3K/AKT/mTOR pathway, thus affecting pain perception. These findings suggested that alterations in Sema3A expression and eIF2 alpha phosphorylation were involved in the development of neuropathic pain, providing potential new targets for clinical pain-relief drug development. Perspective: The expression of Sema3A in DRG neurons was decreased following peripheral nerve injury. Elevating Sema3A levels alleviated neuropathic pain by inhibiting the PI3K/Akt/mTOR pathway and eIF2 alpha phosphorylation, thus affecting ion channel expression in DRG of neuropathic pain model animals. This highlighted Sema3A as potential therapeutic targets for pain relief.