Rhodiola rosea glycosides modulate ERβ/BNIP3-mediated mitochondrial autophagy in cerebral ischemic neuroprotection

Abstract

Objectives: Objective To investigate the neuroprotective effect and mechanism of Rhodiola rosea glycosides(SAL) on cerebral ischemia/reperfusion injury (CIRI) rats through the mitochondrial autophagy pathway mediated by estrogen receptor β (ERβ)/B-cell lymphoma-2/adenovirus E1B interacting protein 3 (BNIP3). Methods: 135 SD rats were divided into OVX and model groups (OVX+MCAO/R),estradiol control group (OVX+MCAO/R+E2), ERβ inhibitor group (OVX+MCAO/R+SAL+PHTPP), autophagy inhibitor group (OVX+MCAO/R+SAL+Mdivi-1), and SAL low,medium, and high dose group (OVX+MCAO/R+SAL). MCAO/R+SAL), the middle cerebral artery embolism (MCAO/R) model was constructed using the wire embolism method, and reperfusion was performed for 24h after 1h of ischaemia. Neurological function scoring was performed after 24h of reperfusion; TTC staining was used to detect the volume of cerebral infarction; water content of brain tissue was determined by wet and dry gravimetry; the permeability of blood-brain barrier was determined by Evans blue (EB) content; the levels of oestrogen (E2), superoxide dismutase (SOD) and malondialdehyde (MDA) were analysed by the kit; neuron pathology was observed on the ischemic side by hematoxylin and eosin (HE) staining; and the damage of neuron in brain tissue by Nissl staining was observed by the kit. Nissl staining was used to observe neuronal damage in brain tissue; transmission electron microscopy (TEM) was used to observe mitochondrial autophagosomes; and Western blotting was used to detect the expression of ERβ and autophagy-related proteins, BNIP3, NIX, Beclin-1 and LC3. Results: There was no statistical difference (P>0.05) in Longa score, TTC, brain water content, EB, E2 and oxidative stress level, HE, Niehl's staining and transmission electron microscopy in the Con group compared with the OVX group, indicating that removal of the ovaries had no effect on the subsequent experiments; whereas, there was a statistically significant difference (P<0.05) and a decrease in the expression of autophagy-related proteins in the MCAO/R group compared with the E2 and SAL groups, indicating that Mdivi-1 and PHTPP inhibitor groups played a protective role against neural damage compared with the SAL-H group. It indicated that E2 and SAL exerted a protective effect against nerve injury; whereas the two inhibitor groups, Mdivi-1 and PHTPP, were statistically significantly different (P<0.05) compared with the SAL-H group, and the inhibitor group reversed the protective effect of SAL and decreased the expression of autophagy-related proteins, suggesting that SAL may protect neuronal cells through ERβ-mediated mitochondrial autophagy. Conclusions: Conclusion SAL may improve neurological function in cerebral ischemic rats by modulating the level of ERβ/BNIP3-mediated mitochondrial self, providing a new way for drug development based on SAL combined with ERβ as a drug for cerebral ischemia.