Targeting astrocytic Nrf2 by Trilobatin alleviates lipopolysaccharide-induced depressive-like behaviors and cognitive impairment in mice: Mechanistic insights into gut microbiota and metabolites modulation.

BACKGROUNDClinical 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.

OBJECTIVEThe 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.

METHODSNeuroprotective 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).

RESULTSTLB 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.

CONCLUSIONOur 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.