Exploring the role of zolpidem in alleviating cognitive and motor impairments in chronic cerebral hypoperfusion: a rat model study with in vivo and in silico insights.

The ε-containing GABA(A) receptors (GABAARs), a lesser-studied subtype within the GABAAR family, have garnered attention due to their distinct pharmacological properties and potential involvement in brain injury. Zolpidem (ZPM), a widely used Z-drug, is known to induce paradoxical effects in patients with brain injury, although the underlying molecular mechanisms remain unclear. In this study, a chronic cerebral hypoperfusion (CCH) rat model was established using Permanent Bilateral Occlusion of the Common Carotid Arteries (PBOCCA), followed by administration of ZPM at doses of 1.0, 2.0, and 4.0 mg/kg. Behavioral assessments demonstrated that the 1.0 mg/kg dose of ZPM significantly improved spatial learning and memory acquisition (P<0.01) and enhanced memory retention (P<0.001), whereas higher doses resulted in sedation and cognitive impairment. Immunohistochemical analysis revealed an upregulation of the ε subunit expression in the hippocampal CA1 and CA3 regions of CCH rats (P<0.05), suggesting alterations in receptor composition in response to cerebral hypoperfusion. Further investigation of ZPM's interaction with ε-containing GABAARs (specifically the α1β2ε subtype) was conducted using in silico techniques. Molecular docking identified the α1+/ε- binding interface as a favorable ZPM binding site, with key residues being either conserved or suitably replaced. Molecular dynamics simulations demonstrated that ZPM stabilizes the receptor while permitting conformational flexibility, consistent with its role as a positive allosteric modulator. These findings provide evidence that ZPM interacts with ε-containing GABAARs, potentially explaining its paradoxical effects observed in brain injury models.