Minocycline attenuates neurological impairment and regulates iron metabolism in a rat model of traumatic brain injury

There is currently no effective treatment for neurological impairment caused by traumatic brain injury (TBI). It has been reported that excessive iron production in the brain may be a key factor in neurological impairment. In the present study, we investigated the effects of minocycline, a semi-synthetic tetracycline antibiotic, against TBI-induced neurological impairment and explored its underlying mechanism. Neurological impairment was assessed by foot-fault test, cylinder test, wire hang test, and Morris water maze. Nissl staining was performed to evaluate cell viability in the brain. The iron concentrations in cerebrospinal fluid (CSF), serum, and brain tissues were examined. The Fe2+- and Fe3+-chelating activity of minocycline was measured. Finally, the expression levels of important iron metabolism proteins ferritin, transferrin receptor 1 (TfR1), divalent metal transporter 1 (DMT1), ferroportin 1 (FPN1), and hepcidin in the hippocampus and cortex were measured by Western blot analysis. The results indicate that minocycline significantly attenuated the neurological impairment caused by TBI and increased neuronal viability. Minocycline showed a Fe2+- and Fe3+-chelating activity in vitro and reduced the iron concentration in CSF and brain tissues (cortex and hippocampus). Minocycline also inhibited the overexpression of ferritin and TfR1, but did not affect the expression of DMT1. Minocycline restored the expression of FPN1 by decreasing the expression of hepcidin. In conclusion, minocycline may attenuate neurological impairment caused by TBI and regulate iron metabolism.