Effect of total flavonoids of hawthorn leaves on spinal cord injury via inhibiting microglia activation

Objective:To exolore the effect of total flavonoids of hawthorn leaves(TFHL)on BV2 microglia activated with lipopolysaccharide (LPS) and spinal cord injury (SCI) rats.Methods:BV2 microglia were activated with LPS to establish a neuroinflammatory model.The experiments were divided into normal control group, LPS group and low, medium and high TFHL dose groups.The SCI model was established according to Allen's method.The rats were randomly divided into sham operation group, model group and TFHL group.The mRNA expression levels of TNF-α, IL-1β, IL-6, iNOS, COX-2 were detected by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR).The level of reactive oxygen species (ROS) was detected by flow cytometry.Western blotting was used to detect the protein expressions of TNF-α and IL-6.Basso-Beattie-Bresnahan(BBB)score was used to evaluate the motor function of rats with SCI.HE staining was used to observe the structural integrity of the spinal cord.Results:In cell experiments, compared with normal control group, the mRNA expression levels of TNF-α, IL-6, IL-1β, iNOS, COX-2 in LPS group and TFHL dose groups increased (P< 0.0001); the mRNA expression levels of TNF-α and IL-6 in low TFHL dose group, TNF-α, IL-1β and IL-6 in medium TFHL dose group and TNF-α, IL-1β, IL-6, iNOS and COX-2 in high TFHL dose group were lower than those in LPS group(P< 0.05).Compared with normal control group, the protein expression levels of TNF-α and IL-6 in LPS group and TFHL dose groups increased(P< 0.0001), while the protein expression levels of IL-6 in medium TFHL dose group and TNF-α and IL-6 in high TFHL dose group were lower than those in LPS group(P< 0.01).Compared with normal control group, the levels of ROS in LPS group and TFHL dose groups increased(P< 0.0001), while the levels of ROS in TFHL dose groups were lower than those of LPS group(P< 0.0001).In animal experiments, compared with sham operation group, the BBB scores in model group and TFHL group decreased (P< 0.0001), and the BBB scores in TFHL group on the fifth day and the seventh day were higher than those in model group(P< 0.05).Compared with model group, the spinal cord structure of TFHL group was more complete and cavity area was less.Conclusion:TFHL can improve the inflammatory microenvironment by inhibiting the activation of microglia, thus playing a role in protecting the neuromotor function of injured spinal cord.