Cu(ATSM) Restores Blood–Brain Barrier Abundance of P-Glycoprotein and Improves Cognitive Function in the APP/PS1 Mouse Model of Alzheimer’s Disease

Alzheimer’s disease (AD) is a prevalent neurodegenerative disorder characterized by the accumulation of amyloid-beta (Aβ) peptides in the brain. P-glycoprotein (P-gp), a key efflux transporter at the blood–brain barrier (BBB), plays a crucial role in the clearance of Aβ. Using the APP/PS1 mouse model of familial AD, this study investigated the effect of copper diacetyl bis(4-methyl-3-thiosemicarbazone) (Cu(ATSM)) on brain microvascular abundance and function of P-gp and the associated effects on exogenous Aβ clearance, brain amyloid burden, and cognitive function. Compared to vehicle-treated 10 month-old APP/PS1 mice, Cu(ATSM) (30 mg/kg/day for 56 days) restored brain microvascular P-gp abundance (24.1%) and Cu concentrations (229.8%) as well as significantly reduced brain cortical concentrations of human Aβ42 (hAβ42) (42.1%) in APP/PS1 mice. Cu(ATSM) treatment led to a trend toward improved brain clearance (11.9%) of 125 I-Aβ42 that was cortically injected into APP/PS1 mice compared to vehicle-treated APP/PS1 mice. Importantly, Cu(ATSM) treatment led to significantly improved (43.8% p = 0.0087) learning and long-term spatial memory in APP/PS1 mice, assessed by the Barnes maze paradigm. Inductively coupled plasma mass spectrometric analysis revealed increased Cu concentrations in brain microvessel-enriched fractions. In APP/PS1 mice, Cu(ATSM) restored brain microvascular P-gp abundance, which was associated with lowered cortical hAβ42, and improved long-term spatial memory, indicating neurovascular target engagement accompanied by amyloid lowering and behavioral benefit. Together with established BBB penetration and ongoing safety and tolerability evaluation in neurodegenerative populations, these findings propose Cu(ATSM) as a potential therapeutic application of biometal modulation targeting neurovascular dysfunction and Aβ burden in AD.