BACKGROUND: Clinical and preclinical evidence links major depressive disorder (MDD) and Alzheimer's disease (AD), suggesting MDD treatment could prevent some AD. Dysfunction within the microbiota-gut-brain axis contributes to MDD and AD pathogenesis via dysregulated microbial metabolites. Trilobatin (TLB) functions as a neuroprotective agent modulating gut microbiota. However, its capacity to alleviate depressive-like behavior and cognitive deficits through restoration of gut microbial ecology and metabolite profiles requires clarification.
OBJECTIVE: The present research was designed to examine the impact of TLB on depressive-like behavior and cognitive impairments, and the role of the gut microbiota and metabolites.
METHODS: Neuroprotective effects of TLB on MDD and AD were evaluated using an LPS mouse model exhibiting depressive-like behavior and memory impairment. The principal molecular target of TLB was identified through a combination of single-cell sequencing, surface plasmon resonance, and gene knockout approaches. Mechanistic insights into gut microbiota and metabolites were gained through 16S rRNA sequencing and fecal microbiota transplantation (FMT).
RESULTS: TLB attenuated LPS-induced depressive-like behaviors manifested as lowered sucrose preference, extended immobility, and improved cognitive deficits as reflected by Y-maze and novel object recognition. Mechanistically, TLB directly bound Nrf2, enhanced Nrf2-ARE activity, and suppressed neuroinflammation and oxidative stress. TLB restored gut microbiota homeostasis, elevated Akkermansia muciniphila (AKK) abundance and short-chain fatty acids, and strengthened intestinal tight junction proteins. FMT from TLB-treated mice replicated these benefits in wild-type but not Nrf2-knockout mice. AKK supplementation similarly ameliorated behavioral and cognitive deficits via Nrf2 activation.
CONCLUSION: Our findings reveal that TLB mitigates neuropsychiatric deficits by activating Nrf2, remodeling restructuring gut microbiota and fortifying intestinal barrier function. The Nrf2-mediated microbiota-gut-brain axis is suggested as a potential therapeutic target for MDD and AD, positioning TLB as a promising natural Nrf2 activator.
Gut-Brain Axis