Pycnogenol achieves neuroprotective effects in rats with spinal cord injury by stabilizing the mitochondrial membrane potential

Objectives: In this study, we aimed to verify the neuroprotective effects of pycnogenol (PYC) on spinal cord injury (SCI) and to determine the underlying mechanisms.

Methods: Male Wistar rats were selected to establish a model of SCI in accordance with the Allen's protocol. The rats in the PYC group were treated with 100 mg/kg PYC by intraperitoneal injection 15 minutes after SCI. The Basso, Beattie and Bresnahan (BBB) scale was used to evaluate locomotor activity. The superoxide dismutase (SOD) activity and malondialdehyde (MDA) production were detected by ELISA. The expression of Cleaved-caspase 3, Bcl-2, Bax and the levels of Cytochrome c (Cyt-c) were analysed by Western blot or Immunohistochemistry. Furthermore, we used the JC-1 fluorescent probe to analyse the mitochondrial membrane potential (ΔΨm).

Results: The rats that received PYC had significantly higher BBB scores than the control lesion rats. PYC treatment resulted in reduced bleeding in spinal cord tissue and proliferation of glial cells, greater numbers of anterior horn neurons, more complete structures of residual neurons, and significant improvement in Nissl body morphology. In addition, PYC reduced MDA production and increased SOD activity. The mitochondrial membrane potential (MMP) was significantly increased in the PYC treatment group compared with the SCI group. In addition, PYC decreased the expression of Cleaved-caspase 3 and Bax and the release of Cyt-c and increased the expression of Bcl-2 in the SCI rats.

Conclusions: The above findings suggested that PYC can improve motor function and reduce neuronal apoptosis after SCI by stabilizing the MMP through the inhibition of oxidative stress.

Abbreviations: DMSO: dimethyl sulfoxide; IHC: immunological histological chemistry; MDA: malondialdehyde; PBS: phosphate buffered saline; PMSF: phenylmethanesulfonyl fluoride; PVDF: polyvinylidene difluoride; PYC: Pycnogenol; RIPA: radio immunoprecipitation assay; SCI: spinal cord injury; SOD: superoxide dismutase.

Keywords: Spinal cord injury; antioxidant; apoptosis; mitochondrial membrane potential; pycnogenol.