Influence of kindlin-1 on astrocyte activation in the spinal cord of rats with neuropathic pain

Objective To investigate the effect of kindlin-1 on astrocyte activation in the spinal cord of rats with neuropathic pain. Methods A total of 18 male 10-12-week-old SD rats, weight 250-280 g, were divided into three groups according to the random number table method (n=6): a sham operation group (group S), a neuropathic pain group (group NP) and a kindlin-1 inhibition group (group K). A neuropathic pain model was established by chronic constriction of the sciatic nerve. The sciatic nerve of group S was only being exposed without ligation. Rats in group K were intrathecally injected with short hairpin RNA (shRNA) 21 d before surgery to inhibit the expression of kindlin-1. Those in groups S and NP were intrathecally injected with viral vector 21 d before surgery for control. The paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were measured 1 d before surgery and 1, 4, 7, 10 d and 13 d after surgery, respectively. When pain threshold measurement finished 13 d after surgery, the rats were sacrificed to collect the spinal cord tissue. The expression of kindlin-1 and astrocytes were detected by immunofluorescent double staining. Also, the expression of kindlin-1 in the spinal cord was measured by Western blot. Results Compared with group S, rats in group NP had reduced PWMT and shortened PWTL as well as up-regulated expression of kindlin-1 protein in the spinal cord 4, 7, 10 d and 13 d after surgery. Meanwhile, increases in optical density (D) value of kindlin-1 and astrocyte activation rate were also seen in group NP (P<0.05). Compared with group NP, group K had increased PWMT and extended PWTL as well as down-regulated expression of kindlin-1 in the spinal cord 4, 7, 10 d and 13 d after surgery. Meanwhile, decreases in D value of kindlin-1 and astrocyte activation rate were seen in group K (P<0.05). Conclusions Kindlin-1 is involved in the activation of astrocytes in the spinal cord of rats with neuropathic pain. Key words: Kindlin-1; Neuropathic pain; Astrocyte; Spinal cord