Effects of tetramethylpyrazine on microglia activation in spinal cord compression injury of mice

Secondary mechanisms, including inflammation and microglia activation, serve as targets for the development and application of pharmacological strategies in the management of spinal cord injury (SCI). Tetramethylpyrazine (TMP), an active ingredient of Ligusticum wallichii (chuanxiong), has shown anti-inflammatory and neuroprotective effects against SCI. However, it remains uncertain whether the inflammation-suppressive effects of TMP play a modulatory role over microglia activation in SCI. The present study investigated the effects of TMP on microglia activation and pro-inflammatory cytokines in spinal cord compression injury in mice. For a real-time PCR measurement of pro-inflammatory cytokines, SCI was induced in mice by the clip compression method (30 g force, 1 min) and TMP (15 or 30 mg/kg, i.p.) was administered once, 30 minutes before the SCI induction. For immunohistochemistry, TMP (30 mg/kg, i.p.) treatment was given three times during the first 48 hours after the SCI. 30 mg/kg of TMP treatment reduced the up-regulation of TNF-α, IL-1β and COX-2 mRNA in the spinal tissue at four hours after the SCI induction. TMP also significantly attenuated microglia activation and neutrophil infiltration at 48 hours after the SCI induction. In addition, iNOS expression in the spinal tissue was attenuated with TMP treatment. These results suggest that TMP plays a modulatory role in microglia activation and may protect the spinal cord from or potentially delay secondary spinal cord injury.