Minocycline Promotes BDNF Expression of N2a Cells via Inhibition of miR-155-Mediated Repression After Oxygen-Glucose Deprivation and Reoxygenation.

Minocycline, an anti-infective agent of a tetracycline derivative, is reported to improve behavioral functional recovery after cerebral ischemia via enhancing the levels of brain-derived neurotrophic factor (BDNF). However, the precise mechanisms that minocycline targets to enhance the expression of BDNF are not fully defined. In the present study, we observed the neuroprotective effect and its potential mechanisms of minocycline using oxygen-glucose deprivation/reoxygenation (OGD/R)-treated N2a cells. We found that 50 µM minocycline protected against neuronal apoptosis induced by OGD/R injury, with increased expression ratio of Bcl-2/Bax and reduced expression of caspase-3. Interestingly, minocycline resulted in the up-regulation of only BDNF protein, not BDNF mRNA in N2a cells treated with OGD/R. Furthermore, we found that minocycline inhibited OGD/R-induced up-regulation of miR-155 targeted BDNF transcripts. Moreover, miR-155 mimic could partially abolish the neuroprotective effects of minocycline via inhibiting the levels of BDNF protein. These findings suggest that minocycline is neuroprotective against ischemic brain injury through their modulation of miR-155-mediated BDNF repression.