Mitoquinone attenuates blood-brain barrier disruption through Nrf2/PHB2/OPA1 pathway after subarachnoid hemorrhage in rats.

BACKGROUND AND PURPOSE: Mitochondrial dysfunction is involved in the mechanism of early brain injury (EBI) following subarachnoid hemorrhage (SAH). Blood-brain barrier disruption is a devastating outcome in the early stage of SAH. In this study, we aimed to investigate the role of a mitochondria-related drug Mitoquinone (MitoQ) in blood-brain barrier disruption after SAH in rats.

METHODS: A total of 181 male Sprague-Dawley SAH rats with the endovascular perforation model were utilized. Intraperitoneal MitoQ was given 1 h (h) post-SAH. Cerebroventricular ML385, an inhibitor of NF-E2-related factor 2 (Nrf2) and Small interfering ribonucleic acid (siRNA) for Prohibitin 2 (PHB2) were injected respectively 24 h and 48 h before SAH. Neurological function evaluation was performed before sacrifice. SAH grade was measured during the sacrifice of each animal. Brain water content was performed at 24 h. Co-immunoprecipitation was used to demonstrate the relationship of proteins Nrf2 and PHB2. Mitochondrial and cytoplasmic fractions were gathered using mitochondria isolation kits. Pathway related proteins were investigated with Western blot and immunofluorescence staining. Transmission electron microscopy was performed for mitochondrial morphology.

RESULTS: Expression of Nrf2 levels peaked at the 3 h time point following SAH and then decreased to normal levels at 24 h, while PHB2 and Optic Atrophy 1 (OPA1) decreased at 24 h and 72 h after SAH compared with the Sham group. MitoQ treatment attenuated neurological deficits and brain edema, thereby resulting in a decreased expression of Albumin, while an increase of Nrf2, PHB2, OPA1 and Claudin-5 proteins compared with SAH + vehicle group. With co-immunoprecipitation, Nrf2 and PHB2 were further demonstrated to show their interaction. And MitoQ administration lead to more binding of the two proteins. ML385 abolished the effects of MitoQ on neurobehavior and protein levels post-SAH. Similarly, PHB2 siRNA reversed the neuroprotection of MitoQ administration with the decreased expression of PHB2 and OPA1 after SAH. Further, MitoQ treatment improved mitochondrial morphology after SAH with an increase of PHB2 and OPA1 in mitochondrial extraction.

CONCLUSIONS: MitoQ attenuates blood-brain barrier disruption via Nrf2/PHB2/OPA1 pathway after SAH in rats. MitoQ may serve as a potential therapeutic strategy for SAH patients.