Abstract:

Objective To discuss the promotion effect of overexpression of circular RNA （circRNA）_ITCH on spinal cord injury （SCI） in the rats， and to clarify its possible mechanism. Methods The rat model of SCI was established by modified Allen’s method. The successfully modeled rats were randomly divided into sham operation group， SCI model group （SCI group）， empty adeno-associated virus group （AAV-NC group） and circ_ITCH overexpression adeno-associated virus group （AAV-circ_ITCH group）， with 15 rats in each group. Microsyringe was used to inject 6 μL of AAV-circ_ITCH and AAV-NC into the injured spinal cord of rats for intervention， and the rats in sham group and SCI group were injected with the same volume of normal saline. Inclined plane test and BBB locomotor rating scale were used to evaluate the hind limb motor function of rats in various groups； real-time fluorescence quantitative PCR was used to detect the expression levels of circ_ITCH in the spinal cord injury tissue of rats in various groups； HE staining was used to observe the pathomorphological manifestations of the spinal cord injury tissue of the rats in various groups； enzyme-linked immunosorbent assay was used to detect the levels of interleukin-1β （IL-1β）， interleukin-6 （IL-6） and tumor necrosis factor-α （TNF-α） in spinal cord injury tissue of the rats in various groups； Western blotting method was used to detect the expression levels of glial fibrillary acidic protein （GFAP）， neurocan and vimentin proteins in spinal cord injury tissue of the rats in various groups； immunofluorescence method was used to detect the expression of GFAP protein， a marker of astrocyte activation， in the spinal cord injury tissue of rats in various groups. Results Compared with sham operation group， the rats in SCI group showed obvious spinal cord tissue injury， the inclined plane angle and BBB score were significantly decreased （P<0.05）， the expression level of circ_ITCH in the spinal cord injury tissue was significantly decreased （P<0.05）， the levels of IL-1β， IL-6 and TNF-α were significantly increased （P<0.05）， and the expression levels of GFAP， neurocan and vimentin proteins as well as the fluorescence intensity of GFAP protein were significantly increased （P<0.05）. Compared with SCI group， the rats in AAV-circ_ITCH group showed significantly ameliorated spinal cord tissue injury， the inclined plane angle and BBB score were significantly increased （P<0.05）， the expression level of circ_ITCH in the spinal cord injury tissue was significantly increased （P<0.05）， the levels of IL-1β， IL-6 and TNF-α were significantly decreased （P<0.05）， and the expression levels of GFAP， neurocan and vimentin proteins as well as the fluorescence intensity of GFAP protein were significantly decreased （P<0.05）； in AAV-NC group， there were no statistically significant differences in the above indicators （P>0.05）. Conclusion Overexpression of circ_ITCH can alleviate spinal cord tissue injury in the rats with SCI and promote the recovery of motor function in the rats； its mechanism may be related to inhibiting neuroinflammation and astrocyte activation.

Key words: Spinal cord injury, Circular RNA_ITCH, Astrocytes, Neurological function, Motor function