Melatonin treatment protects against acute spinal cord injury-induced disruption of blood spinal cord barrier in mice.

The spinal cord microcirculation plays a critically important role in maintaining the normal function of spinal cord neurons, glial cells, and axons. Previous researches were largely focused on improved neurological manifestations of spinal cord injury (SCI) while ignoring to improve spinal cord microcirculation disorder after melatonin treatment. Therefore, the mechanism of melatonin that affects blood spinal cord barrier (BSCB) integrity and microcirculation in SCI remains unclear. The present study was performed to investigate the effect of melatonin on the BSCB in a SCI mice model. Melatonin (5, 10, 25, 50, 100 mg/kg i.p.) was administered to mice immediately following SCI. Compared to the 48 h post-SCI group, mice treated with melatonin (50 mg/kg) exhibited significantly reduced BSCB permeability. Additionally, melatonin treatment restrained microvessel loss; attenuated edema; protected the tight junction proteins, endothelial cells, and pericytes; decreased the number of cell apoptosis; and reduced MMP3/AQP4/HIF-1α/VEGF/VEGFR2 expression after SCI. Above all, our results clearly demonstrated that melatonin could stabilize microvascular barrier function and microcirculation of SCI, whose mechanism was to promote the repair of the damaged BSCB.