Background/purpose: Spinal cord injury (SCI) is a devastating medical condition for which no effective pharmacological interventions exist. l-Theanine (LT), a major amino acid component of green tea, exhibits potent antioxidative and anti-inflammatory activities and protects against various neural injuries. Here, we evaluated the potential therapeutic effects of LT on the recovery of behavioral motor functions after SCI in rats and the underlying neuroprotective mechanisms.
Methods: SCI was induced by applying vascular clips to the dura through a four-level T5-T8 laminectomy, and saline or LT (10/30 mg/kg) was intrathecally administered at 1-, 6-, and 24-h post-SCI. At 72-h post-SCI, half of the rats from each group for each parameter were sacrificed, and their spinal cord was excised for measurement of malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase, catalase, tumor necrosis factor-α, interleukin-1β/-6, myeloperoxidase, and caspase-3. The remaining rats from each group were subjected to Bresnahan locomotor-rating scale (BBB), inclined-plane, toe-spread, and hindfoot bar-grab tests at 1-, 4-, 7-, 10-, and 14-days post-SCI.
Results: LT treatment reduced NO and MDA levels, increased antioxidative strength, and markedly suppressed the levels of neuroinflammatory and apoptotic markers in the spinal cord after SCI. Moreover, LT treatment drastically promoted the recovery of behavioral motor functions post-SCI.
Conclusion: Our findings revealed that LT can enhance the recovery of behavioral motor functions after SCI in rats, which related to the suppression of post-traumatic oxidative response, neural inflammation, and apoptosis. This evidence indicates that LT holds considerable potential for use in the clinical treatment/prevention of SCI-induced motor dysfunction.
Keywords: Apoptosis; Inflammation; Oxidative stress; Spinal cord injury; l-theanine.
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