Role of SPP1 in endogenous protective mechanism underlying neuropathic pain in mice with spinal cord injury: relationship with VEGF-AKT signaling pathway / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of secreted phosphoprotein 1 (SPP1) in endogenous protective mechanism underlying neuropathic pain (NP) in mice with spinal cord injury and the relationship with the vascular endothelial growth factor (VEGF)/kinase B (Akt) signaling pathway.Methods:Seventy-two clean-grade healthy female Kunming mice, aged 7-8 weeks, weighing 30-35 g, were divided into 4 groups ( n=18 each) using a random number table method: sham group (Sham group), NP caused by spinal cord injury group (NP group), NP caused by spinal cord injury+ SPP1-siRNA group (NS-siRNA group), and NP caused by spinal cord injury+ adeno-associated virus vector group (NP-EV group). A model of NP was established by a semi-transecting of the spinal cord.AAV-SPP1-siRNA-GFP adenovirus and AAV-vector-GFP adenovirus 7 μl were intrathecally injected in NS-siRNA group and NP-EV group, respectively, and 5 days later the model was established.At 1, 2 and 3 weeks after operation, 6 mice in each group were randomly selected to measure paw withdrawal threshold to mechanical stimulation (PWMT) and tail flick latency (TFL) to thermal stimuli.And then the mice were sacrificed and the ipsilateral injured spinal cord tissues were taken for determination of the expression of SPP1 mRNA (by real-time polymerase chain reaction) and expression of SPP1, VEGF, Akt and phosphorylated Akt (p-Akt) (by Western blot). Results:Compared with group Sham, PWMT was significantly decreased, TFL was shortened, and the expression of SPP1 mRNA, SPP1, VEGF and p-Akt protein was up-regulated at 1, 2 and 3 weeks after operation in NP, NS-siRNA and NP-EV groups( P<0.05). Compared with group NP, PWMT was significantly decreased, TFL was shortened, and the expression of SPP1 mRNA, SPP1, VEGF and p-Akt protein was down-regulated at 1, 2 and 3 weeks after operation in group NS-siRNA( P<0.05). Compared with group NS-siRNA, PWMT was significantly increased, TFL was prolonged, and the expression of SPP1 mRNA, SPP1, VEGF and p-Akt protein was up-regulated at 1, 2 and 3 weeks after operation in group NS-siRNA( P<0.05). Conclusion:SPP1 is involved in the endogenous protective mechanism underlying NP in mice with spinal cord injury, which may be related to the activation of the VEGF/AKT signaling pathway.