Hyperbaric oxygen promotes mitophagy by activating CaMKKβ/AMPK signal pathway in rats of neuropathic pain

Neuropathic pain is a kind of chronic intractable disease. HBO explored the involvement of mitophagy which is associated with energy metabolism by AMPK. CaMKKβ/AMPK signaling pathway may involve in mitophagy process. We randomly divided mice into four groups: C, S, CCI, and CCI + HBO group. Pain-related behaviors were evaluated using mechanical withdrawal threshold and thermal withdrawal latency analysis. Western blot was employed to assess expression of CaMKKβ, pAMPK, AMPK, NIX, BNIP3, and Drp1. Spinal cord was observed under the electron microscope. Immunofluorescence changes in NeuN and CaMKKβ or AMPK were examined. AMPK inhibitor compound C (CC) and CaMKKβ inhibitor STO609 were administrated prior to CCI, respectively. The changes in behaviors and Western blot are examined. HBO upregulated CaMKKβ and pAMPKα expression. NeuN and CaMKKβ were colocalizated in immunofluorescence. HBO can elevate the pain-related behaviors significantly, while it was downregulated by CC or STO609. HBO upregulated NIX, BNIP3, and Drp1 expressive level more significantly than those in CCI group. However, expression was reduced when CC or STO609 were administered. Electron microscopic examination showed that mitophagy was upregulated after HBO treatment. This phenomenon was not observed when CC or STO609 were administered. Our findings suggest that CaMKKβ/AMPK pathway maybe a potential signal pathway on analgesic mechanism of hyperbaric oxygen via mitophagy.