Caffeic acid ameliorates D-galactose-induced brain senescence via the BHMT/NMDAR/CREB axis

Caffeic acid (CA), a natural phenolic compound, exhibits potent neuroprotective properties. This study aimed to elucidate the anti-aging efficacy and central metabolic regulatory mechanisms of CA in D-galactose (D-gal)-induced brain senescence. In vivo , male Sprague-Dawley rats were injected with D-gal (150 mg/kg) for ten weeks, and co-treated with CA for the last eight weeks. Behavioral tests demonstrated that CA significantly reversed D-gal-induced learning and memory impairments. Biochemically and histologically, CA attenuated oxidative stress and neuroinflammation, suppressed neuronal apoptosis, and restored presynaptic and postsynaptic proteins (SYN, PSD95). To uncover the underlying mechanisms, 1 H NMR-based cerebral metabolomics was performed, revealing that CA restored metabolic homeostasis, particularly the levels of betaine and D-aspartic acid. Crucially, protein analysis confirmed that CA significantly upregulated key metabolic enzymes, notably betaine-homocysteine S -methyltransferase (BHMT). To validate this target, a D-gal-induced SH-SY5Y cellular model coupled with small interfering RNA (siRNA) was employed in vitro . Knockdown of BHMT fundamentally abolished the protective effects of CA, unequivocally identifying BHMT as its primary molecular target. CA-driven BHMT activation facilitated the clearance of neurotoxic homocysteine (Hcy), which consequently reactivated NMDARs (NR1, NR2A, NR2B) and the downstream CREB synaptic signaling cascade. In conclusion, CA mitigates D-gal-induced cognitive deficits by targeting the BHMT/NMDAR/CREB metabolic-synaptic axis, highlighting its promising therapeutic potential against age-related neurodegeneration. • Caffeic acid ameliorates D-galactose-induced cognitive deficits and brain senescence in rats. • Caffeic acid restores cerebral metabolic homeostasis, especially D-Asp and betaine levels. • siRNA knockdown confirms BHMT as the primary target of caffeic acid for eliminating toxic Hcy. • Caffeic acid-driven Hcy elimination reactivates the downstream NMDAR/CREB signaling pathway. • Caffeic acid protects against brain aging via the BHMT/NMDAR/CREB metabolic axis.