RESUMO
BACKGROUND:Spinal cord injury involves mechanisms such as oxidative stress,inflammation,apoptosis and autophagy.Activation of autophagy can improve neuromotor function after spinal cord injury and play a protective role in the spinal cord. OBJECTIVE:To investigate the effects of Periplaneta americana powder on hindlimb motor function and the autophagy protein Beclin-1 in the injured site of rats after spinal cord hemisection. METHODS:Thirty Sprague-Dawley rats,6-8 weeks of age,were randomly divided into three groups(n=10 per group).In the sham-operated group,the lamina was just opened to exposure the spinal cord followed by suturing.Normal saline group and Periplaneta americana powder group both underwent left hemisection of the spinal cord to prepare animal models of spinal cord hemisection.The normal saline group was continuously gavaged with normal saline for 14 days,and the Periplaneta americana powder group was continuously gavaged with Periplaneta americana powder for 14 days.The Basso Beattie Bresnahan scale score was performed at the 6th hour,1st day,3rd day,7th day and 14th day after operation to observe the hindlimb motor function.After 14 days of administration,the rats were sacrificed and sampled.Immunohistochemistry,western blot and immunofluorescence were used to detect the expression of Beclin-1 in the injured site of the spinal cord after hemisection. RESULTS AND CONCLUSION:After operation,the Basso Beattie Bresnahan scale scores were gradually increased in the normal saline group and Periplaneta americana powder group.Compared with the sham-operated group,the Basso Beattie Bresnahan scale scores were significantly reduced in the normal saline group and Periplaneta americana powder group at the 6th hour,1st day,3rd day,7th day and 14th day after operation(P<0.05).The Basso Beattie Bresnahan scale scores in the Periplaneta americana powder group were significantly higher than those in the normal saline group at the 7th and 14th days after operation(P<0.05).Immunohistochemical staining showed that Beclin-1 was weakly positive in the sham-operated group,mainly expressed in the cytoplasm;in the normal saline group,Beclin-1 was mainly expressed in the cytoplasm and partially expressed in the nuclear membrane;in the Periplaneta americana powder group,Beclin-1 was mainly expressed in the cytoplasm and partially expressed in the nuclear membrane.The proportion of Beclin-1 positive cells was higher in the normal saline and Periplaneta americana powder groups than in the sham-operated group(P<0.05),while the proportion of Beclin-1 positive cells was higher in the Periplaneta americana powder group than in the normal saline group(P<0.05).Western blot assay and immunofluorescence staining showed that the Beclin-1 protein expression was higher in the normal saline and Periplaneta americana powder groups than in the sham-operated group(P<0.05),and moreover,the Beclin-1 protein expression was higher in the Periplaneta americana powder group than in the normal saline group(P<0.05).To conclude,Periplaneta americana powder could improve the hindlimb motor function of rats with spinal cord hemisection injury,and the mechanism may be that polysaccharides in the Periplaneta americana powder increase the expression of Beclin-1.