Bassiouni, W. | bioRxiv Science

bioRxiv2026

Restoring neurovascular coupling in Alzheimer's disease tauopathy through M1 mAChR modulation

Alzheimer's disease is characterized by progressive cognitive decline and early cerebrovascular dysfunction, including impaired neurovascular coupling (NVC) and reduced cerebral blood flow (CBF). Tau pathology is a major driver of these deficits, yet therapeutic strategies targeting tau-induced neurovascular dysfunction remain limited. The M1 muscarinic acetylcholine receptor (M1 mAChR) is a promising therapeutic target because of its critical role in cognition. We previously demonstrated that pharmacological activation of M1 mAChR improves cognitive function and neuronal survival in amyloid-based Alzheimer's disease mouse models through sex-specific mechanisms. However, whether M1 mAChR activation restores tau-mediated NVC deficits remains unknown. P301S mice were used as a model of tauopathy. Cognitive function was evaluated using the novel object recognition and Morris water maze tests, and NVC was assessed by measuring whisker stimulation-induced changes in CBF using laser speckle contrast imaging. Following baseline measurements, mice received an acute intraperitoneal injection of VU0486846, a selective M1 mAChR positive allosteric modulator (3 mg/kg), and CBF responses were reassessed over time. P301S tau mice exhibited impaired recognition and spatial memory functions, associated with reduced whisker stimulation-induced increase in CBF, indicative of impaired NVC response, while acute treatment with VU0486846 reversed these changes in NVC. This rescuing effect of VU0486846 was observed earlier in female tau mice compared to males, suggesting a sex-biased effect of M1 mAChR modulation. These findings demonstrate that M1 mAChR positive allosteric modulation reverses tau-induced neurovascular dysfunction, supporting M1 mAChR activation as a promising disease-modifying approach for Alzheimer's disease. The earlier improvement observed in females further suggests that therapeutic efficacy is influenced by biological sex.

pharmacology and toxicology↗

bioRxiv2026

Matrix metalloproteinases proteolyze RAB proteins and contribute to cisplatin-induced ototoxicity

Matrix metalloproteinases (MMPs) are rapidly expressed and activated in response to oxidative stress and contribute to various pathological conditions. Cisplatin is a highly effective chemotherapeutic agent; however, its clinical use is limited by its associated permanent hearing loss (ototoxicity). While cispwlatin-induced oxidative stress and inner ear cell death are well-established, the contribution of MMPs remains unclear. In this study, we demonstrate that cisplatin exposure triggers activation of MMP-2 and MMP-9 and expression of an intracellular N-terminal-truncated isoform of MMP-2 in mouse inner ear hair cells. Pharmacological inhibition of MMP-2 and genetic knockdown of Mmp-9 enhanced hair cell survival and attenuated cisplatin-induced inflammation and cytotoxicity. Furthermore, proteomic analysis revealed that proteins involved in intracellular trafficking, including RAB proteins, may serve as potential substrates of intracellular MMP-2 upon cisplatin exposure, pointing to a previously unrecognized mechanism of cisplatin-induced hair cell injury. In vitro analysis confirmed that MMP-2 cleaves RAB9A in response to cisplatin, and in silico analyses predicted MMP-2-preferred cleavage sites on RAB9A. Collectively, our findings identify MMP-2 as a promising therapeutic target for mitigating cisplatin-induced ototoxicity.

pharmacology and toxicology↗