improves cognitive function and alters the hippocampal metabolome of aged Tg2576 and wild-type mice.

Background: Alzheimer's disease (AD) is a growing public health problem in the aging population, with limited treatment options. We previously reported that herb water extract (CAW) attenuates cognitive decline in murine models of AD and aging.

Objective: To explore changes in the hippocampal metabolome associated with CAW's modulation of cognitive function and amyloid-β (Aβ) plaque load in aged Tg2576 and wild-type (WT) mice.

Methods: We compared cognitive function, hippocampal Aβ plaque burden, and hippocampal metabolite profile in 20-month-old Tg2576 female mice and their WT littermates following 3-5 weeks treatment with CAW (0, 200, or 1000 mg/kg/d p.o.). Cognitive testing included contextual fear response (CFR) and novel object recognition task (NORT). Aβ plaque burden was measured via immunohistochemistry. Metabolomic profiles of mouse hippocampi were obtained using liquid chromatography coupled with high resolution tandem mass spectrometry.

Results: CAW treatment resulted in dose-related improvements in CFR and NORT performance of Tg2576 and WT mice. However, while CFR correlated with neurosignaling and glycosylated ceramide levels, NORT performance correlated with lysophosphatidylcholines and oxidized metabolites, and Aβ accumulation was linked to elevated excitatory and suppressed inhibitory neurotransmission. Only a subset of the metabolite changes induced by CAW in Tg2576 mice represented a reversal of metabolite differences between Tg2576 and WT mice, suggesting the involvement of other pathways in CAW's cognitive effects.

Conclusions: Mechanisms underlying CAW's cognitive effects extend beyond reversing metabolic effects of Aβ accumulation. The data support the potential use of CAW to manage memory challenges in aged individuals with or without AD.