Donepezil Improves <scp>PSD95</scp> Expression, Mitigates Neuroinflammation via <scp>PI3K</scp> /Akt/ <scp>NF</scp> ‐ <scp>κB</scp> and Mitochondrial Dysfunction in a Rodent Model of Subarachnoid Haemorrhage

Mitochondrial dysfunction is a known contributor to subarachnoid haemorrhage (SAH) induced early brain damage (EBI), leading to poor neurological outcomes. An experimental SAH model was induced in adult male Wistar rats using endovascular perforation. Donepezil, an acetylcholinesterase (AChE) inhibitor (1 or 2 mg/kg body weight), was administered intraperitoneally 4 h after SAH. The severity of cerebral cortex injury was assessed using blood clot grading, behavioral tests and H and E staining. We carried out an assessment of neuroinflammatory markers using western blotting and immunofluorescence. Additionally, we examined neuronal architecture using H and E staining, measured mitochondrial redox imbalance or ROS and membrane potential (Δѱm) and analyzed mitochondrial morphology using transmission electron microscopy (TEM). Apoptotic markers and mitochondrial respiratory complexes were assessed by western blotting. Our results indicated that donepezil treatment significantly upregulated PSD95, α7-AChR, CaMKII, BDNF, CREB, and PI3K expression in cerebral cortical neurons in response to SAH. This was accompanied by improved neurological function, reduced brain edema, decreased neuronal degeneration, and increased levels of OXPHOS and ATP. In the cerebral cortex, donepezil inhibited mitochondria-associated neuronal apoptosis after SAH as revealed by increased membrane potential integrity of mitochondria, reducing the ratio of Bax to Bcl-2 and inhibiting caspase-3 activity. Additionally, donepezil upregulated synaptic proteins (PSD95), strengthening synaptic connections and supporting spatial working memory circuits via the neurotrophic factor BDNF in post-SAH rats. Our research concludes that donepezil has neuroprotective benefits by inhibiting SAH-induced mitochondrial-mediated cell death through the regulation of Drp1-mediated mitochondrial morphology changes.