Quercetin promotes locomotor function recovery and axonal regeneration through induction of autophagy after spinal cord injury.

Quercetin (Que), one of the flavonoids, exerts numerous actions on the central nervous system. However, the roles and underlying mechanism of Que in locomotor function recovery and axonal regeneration following spinal cord injury (SCI) have not been fully elucidated. A rat model of spinal cord injury (SCI) was established at T10 using the modified Allen's method. The results in our study indicated that Basso, Beattie and Bresnahan (BBB) locomotor scores were significantly higher after Que treatment. Additionally, Que administration cut down the latency of somatosensory evoked potentials (SEP) and motor evoked potentials (MEP), increased the amplitude of MEP and SEP following SCI. Hematoxylin-eosin (HE) staining demonstrated that Que administration reduced lesion size and cavity formation. Biotinylated dextran amine (BDA) anterograde tracing revealed that BDA positive fibres were increased by Que following SCI. Immunofluorescence staining revealed that Que elevated 5-hydroxytryptamine (5-HT) positive nerve fibres and neurofilament-200 (NF-200) positive neurons, reduced glial fibrillary acidic protein (GFAP) positive astrocytes. In addition, Que inhibited GFAP expression, increased both NeuN and NF-200 expression and facilitated the spinal cord energy metabolism. Moreover, Que increased 18 F-FDG uptake in a time-dependent manner. Furthermore, Que increased Beclin 1 and LC3 II expression, blocked the phosphorylation of Akt, mTOR and p70S6K. 3-methyladenine (3-MA) partly abolished the neuro-protective roles of Que following SCI. Taken together, our study suggested that Que might promote locomotor function recovery, axonal regeneration and energy metabolism through induction of autophagy via Akt/mTOR/p70S6K pathway.