Effect and mechanism of SS31 peptide on autophagy after spinal cord injury in rats

Abstract

Objective To explore the effect of SS31 peptide on autophagy after spinal cord injury (SCI) and possible mechanism. Methods Allen method was used to construct the spinal cord injury model in rats. Sprague-Dawley rats were randomly divided into sham surgery group (sham group), SCI group and SS31 peptide group, with 30 rats in each group. The sham group only received laminectomy. The rats in SCI group were sustained SCI and were given no intervention. The rats in SS31 group received SS31 peptide injection after SCI. Scores of Basso Beattie Bresnahan (BBB) motor functions were assessed at 6 h, 1, 3, 7 and 14 d after the injury. The changes in related proteins of Beclin-1 and LC3-II were also detected. Results Scores of BBB scale at 6 h and at days 1, 3, 7 and 14 after injury in SCI group (0, 1.7±0.4, 3.5±0.6, 6.1±0.7, 10.1±0.6) and SS31 peptide group (0, 2.5±0.7, 4.1±0.7, 9.3±0.6, 13.4±0.6) were lower than that in sham group (21 at all time points) (P 0.05). Compared with sham group, the expression of Beclin-1 in SCI group and SS31 peptide group was increased, reached a peak at day 3 (1.478±0.030, 1.841±0.051), remained high level at day 7 (1.302±0.049, 1.551±0.032) and showed high expression at day 14 (1.252±0.048, 1.471±0.062) (P 0.05). Conclusion SS31 peptide can improve motor function and enhance the autophagy of nerve cells after SCI in rats, which may be one of the mechanisms for SS31 peptide treating spinal cord injury. Key words: Spinal cord injuries; Autophagy; Beclin-1