To evaluate the regulation effect of tetramethylpyrazine on microRNA-214-3p (miR-214-3p) in the spinal cord injury (SCI) rats model and to elucidate the neuroprotective effect and its mechanism of tetramethylpyrazine after SCI.

Ten Sprague-Dawley rats were used to establish the SCI rats model, and the expression levels of miR-214-3p and Bcl2l2 were detected by qRT-PCR and Western blotting at 7 days post-SCI. BBB scoring test was performed to evaluate the motor functional recovery at 21 days post-SCI. Twenty-five SCI rats were randomly assigned to five groups: SCI negative control (NC) group, tetramethylpyrazine (TMP) group, miR-214-3p agomir group, TMP/agomir group and the sham group. The rats were given a two-week injection treatment with or without TMP. The expression levels of miR-214-3p, Bcl2l2, Bax and caspase 3 were measured by qRT-PCR and Western blotting at 7 days after injection. Terminal deoxynucleotidyl transferase (TdT) −mediated dUTP Nick-End Labeling (TUNEL) assay was performed to detect cell apoptosis in vivo. Luciferase activity was measured to verify the miR-214-3p target site in the 3′-UTR of Bcl2l2 mRNA. TMP treatment was also performed to injure primary cultured neuron cells and cell apoptosis in vitro was determined by flow cytometry.

MiR-214-3p was up-regulated while anti-apoptotic protein Bcl2l2 was downregulated post-SCI. TMP inhibited the apoptosis in vivo via decreasing the levels of miR-214-3p and increasing the expression level of Bcl2l2. A potential target site of miR-214-3p in the 3′UTR of Bcl2l2 mRNA was identified and validated by luciferase reporter assay. Furthermore, TMP could effectively inhibit neuron cells apoptosis in vitro.

TMP alleviated neural apoptosis in injured spinal cord via down-regulation of miR-214-3p.