| Background and ObjectiveSpinal cord injury (SCI) is a common and serious damage of central nervous system, often caused by the trauma or disease, and results in severe motor and sensory disfunctions. The primary mechanical injury in spinal cord always leads to a series of pathological changes, including local microcirculatory disturbance, oxidative stress, infiltration of activated neutrophils, necrosis and apoptosis, etc, what is worse, the injury is always a part of systemic traumas. The number of medicines which have exact effects on SCI is very small, and most of them have been confirmed to have serious side effects. This urges us to find new medicines to cure the dreadful disease. Former studies have confirmed that melatonin (MT) as a remarkable therapeutic effect of SCI in rats, but its mechanisms of action have not been fully elucidated.Material and methods60male Sprague-Dawley(SD) rats were randomly divided into3groups:SCI group (A) for SCI and intraperitoneal injection of dehydrated alcohol of equal volume in group B (the solvent of MT); MT treatment group (B) for SCI and intraperitoneal injection of MT(100mg/kg); Sham group for laminectomy only. The SCI animal model was established by using modified Allen’s weight drop(WD) method with the force of50gcf at T12level.12h later, the function of the spinal cord was assessed by Basso Beattie Bresnahan locomotor rating scale (BBB scale) then all the rats were sacrificed. The blood and spinal cord samples were taken to measure the levels of NGF、NGF mRNA、MDA and SOD.8samples of spinal cord were taken randomly in each group to undertake histological examination using HE and Immunohistochemical SP staining methods. Statistical analysis was performed with the SPSS17.0software. All values were expressed as mean±standard deviation (x±s) Statistical analysis of data was performed using a one-way analysis of variance (ANOVA), least significant difference test (LSD-t) and Tamhane’s T2test. Statistical significance was assumed for P<0.05. Results1.12h after the operation, group B had the highest level of NGF mRNA expression in spinal cord tissues and NGF in serum, Sham group had the lowest level of that, the differences among3groups were significant(P<0.01).2. The outcomes of MDA assay showed that group A had the highest level (P<0.01), the difference between group B and Sham group had no statistical significance (P>0.05).3. The results of SOD assay showed that Sham group had the highest level, group A had the lowest level, the differences among3groups were significant (P<0.01).4. Severe lower limbs neurological dysfunction was observed in group A and B, but the difference between them in BBB scale had no statistical significance (P>0.05).5. According to histological findings, melatonin could improve the histopathology of the injured spinal cord and could also increase the level of NGF within the spinal ventral horn and the nearby white matter (P<0.01)Conclusions1. This study indicates that melatonin’s therapeutic effect of spinal cord injury is through its antioxidation and enhancement of NGF expression.2. Melatonin conducts the antioxidation partly and indirectly by protecting the activity of SOD.3. The intraperitoneal injection of MT (100mg/kg) can not improve the motor disfunction of the rats12h after SCI. |
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