Dexmedetomidine Exerts Multi-level Effects to Ameliorate Alzheimer's Disease Pathology in the Adult Zebrafish Brain

Alzheimer's disease (AD) is a complex neurodegenerative condition involving β-amyloid (Aβ) deposition, tau abnormalities, neuroinflammation, neuronal degeneration, and progressive impairment of cognitive functions. Despite extensive research, effective disease-modifying therapies remain limited, highlighting the need for translationally relevant models and repurposable therapeutic candidates. Dexmedetomidine (DEX), an α2-adrenergic receptor agonist with known neuroprotective properties, was investigated in an adult zebrafish model of AD established through cerebroventricular administration of Aβ42. DEX treatment significantly reduced Aβ accumulation and was associated with reduced amyloidogenic gene expression, indicating transcriptional changes in amyloidogenic pathway-related genes. DEX attenuated neuroinflammation by reducing glial activation, lowering pro-inflammatory cytokine gene expression, and increasing expression of the anti-inflammatory gene il10. Immunofluorescence assessment further demonstrated reduced astrogliosis and preserved neuronal marker integrity, as indicated by increased HuC/D levels. Interestingly, DEX attenuated Aβ-induced proliferative responses, characterized by decreased PCNA expression, while enhancing cleaved caspase-3 levels, suggesting changes in proliferation and apoptotic signaling under Aβ stress conditions. Behavioral assessments further demonstrated that DEX alleviated Aβ42-induced anxiety- and aggression-like behaviors, improving behavioral phenotypes in this model. Overall, these findings underscore the multi-level effects of DEX in modulating AD-related pathological features. As a clinically available agent, DEX represents a promising candidate for repurposing in neurodegenerative disease contexts. Further preclinical studies in mammalian models are warranted to validate its translational relevance and therapeutic potential.