Efficacy of Minocycline in Neural Stem Cells Proliferation after Traumatic Brain Injury

BACKGROUND: Neuroinflammation is an important secondary injury mechanism that contributes to neurological impairments after traumatic brain injury (TBI). There is a robust evidence that neuroinflammation will diminish neurogenesis after TBI. Therefore, strategies to attenuate the inflammatory responses are potential to increase neurogenesis following TBI. Minocycline, a second-generation tetracycline antibiotic derivate, has potent anti-inflammatory effect by reducing microglial activation and suppressing some pro-inflammatory cytokines. AIM: The aim of this study is to investigate if minocycline could enhance neurogenesis after TBI. METHODS: Thirty Sprague Dawley rats were randomized into three treatments group, i.e., sham-operated controls, closed head injury (CHI), and CHI with minocycline. We used the modified Feeney’s weight-drop model for making CHI. For the treatment group, we gave minocycline per oral (50 mg/kg) twice daily for the first 2 days followed by 25 mg/kg once daily for 3 consecutive days. Animals were sacrificed on day 5. To assess the proliferation capacity of neural stem cells (NSC), we performed immunohistochemistry staining with SOX2, brain-derived neurotropic factor (BDNF), and NFR. Cell counts were carried out using light microscope with 1000 times magnification in 20 high-power fields. RESULTS: SOX2, NF-E2-related factor 2 (NRF-2), and BDNF were upregulated in the CHI group compared to the sham-operated group (p < 0.05). NRF-2, BDNF, and SOX2 were upregulated also significantly in the CHI+ minocycline group compared to the sham-operated group and the CHI group (p < 0.05). CONCLUSION: Minocycline increased the proliferation capacity of NSC.