Salidroside facilitates neuroprotective effects in ischemic stroke by promoting axonal sprouting through promoting autophagy.

Background: Ischemic stroke is a common cerebrovascular disease characterized by high incidence, disability, mortality, and recurrence. The limitations of current pharmacological treatments, which have primarily single neuroprotective action and a narrow therapeutic time window, lead to unsatisfactory therapeutic efficacy. Activation of autophagy can facilitate neural regeneration.

Objective: To clarify whether salidroside can promote axonal sprouting through autophagy resulting in protecting neurons.

Methods: In vivo, a Middle Cerebral Artery Occlusion/reperfusion (MCAO/IR) model was used, and in vitro, an Oxygen-Glucose Deprivation/Reoxygenation (OGD/R)-induced primary neuronal cell model was employed to evaluate the neuroprotective effects of salidroside. BDA neurotracer, immunofluorescence, and Western blot (WB) were utilized to determine its impact on axonal sprouting and the levels of related proteins (MAP2, GAP43, and PSD-95). Proteomics, transmission electron microscopy (TEM), and WB were applied to identify the effects on autophagy-related proteins (beclin1, LC3, p62, and LAMP2), autophagosomes and lysosomes. The mechanism of salidroside in promoting axonal sprouting through inducing autophagy was further confirmed by blocking with the autophagy inhibitor 3-MA.

Results: Salidroside reduced neurologic deficits and infarct volume induced by MCAO/IR in vivo and protected OGD/R induced primary neuronal cells in vitro. Both in vivo and in vitro, it increased the number and length of axons and upregulated the expression of key axonal proteins (MAP2, GAP43, and PSD-95) and mediated autophagy-related proteins. Mechanistic studies showed that the promoting effects of salidroside on autophagy and axonal sprouting disappeared after the blockade by 3-MA.

Conclusion: This study reports for the first time that the neuroprotective effect of salidroside in ischemic stroke can be executed through mediating autophagy-related protein (beclin1, LC3, p62, and LAMP2), resulting in induced axonal sprouting or mature protein (MAP2, GAP43, and PSD-95).