Modulation of the microRNA-378e/myocyte enhancer factor 2D axis by gastrodin in preventing cognitive dysfunction post-subarachnoid haemorrhage.

Subarachnoid hemorrhage (SAH) is a cerebral hemorrhagic disorder that can severely damage the brain and lead to cognitive impairment. Gastrodin (GAS) is the main bioactive ingredient extracted from Gastrodiae Rhizoma, which has neuroprotective effects against brain injury. The aim of this study was to investigate the potential treatment of cognitive dysfunction after SAH and to explore the mechanism of action of the multi-targeted drug Gastrodin to alleviate cognitive dysfunction after SAH. The SAH rat model was established by vascular puncture, and the target sequences were delivered to rats via adenoviral vectors. Dual luciferase reporter gene assay and RNA immunoprecipitation (RIP) assay were used to verify the targeting relationship between microRNA-378e (miR-378e) and myocyte enhancer factor 2D (MEF2D). Neurologic scores of rats were evaluated according to the modified Garcia scoring system. Learning memory ability of rats was determined by Morris water maze assay and open field assay. Rat brain edema index was determined by wet/dry method. Blood-brain barrier (BBB) permeability was assessed by Evan's blue assay. The pathological changes in the tissues were analyzed using hematoxylin-eosin (HE) staining, and the apoptosis of neuronal cells was analyzed using TUNEL. Reactive oxygen species (ROS) generation was observed using fluorescence microscopy. Oxidative stress was assessed through the analysis of ROS, malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH). Tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) levels in hippocampal tissue were measured by ELISA. A direct targeting relationship existed between miR-378e and MEF2D. The number of TUNEL-positive neurons in the hippocampus was significantly reduced after Gastrodin treatment compared to SAH rats (P<0.05). This finding was associated with the observed decrease in the level of the apoptosis-related Bcl-2-associated X (Bax) protein, the rise in B-cell lymphoma 2 (Bcl-2) expression, and the inhibition of cleaved caspase-3 activation after SAH (P<0.05). GAS effectively alleviated SAH-induced brain edema and blood-brain barrier dysfunction and reduced brain water content and Evan's blue in brain tissue (P<0.05). GAS significantly improved the learning and memory abilities of rats as tested by Morris water maze and open field experiments. In addition, the up-regulation of both oxidative stress and inflammatory response-related factors in tissues after SAH were reversed by GAS administration (P<0.05). Summing up the results, GAS ameliorates SAH-induced cognitive deficits and brain damage by modulating the miR-378e/MEF2D axis, exerting a cerebroprotective effect. This may provide some new clues for future therapies to mitigate the damage after SAH.