Erzhi Pill restores hippocampal energy metabolism and synaptic integrity via GSK3β to alleviate cognitive decline, with GPR30 involvement

Objective This study investigated whether Erzhi Pill (EZP) ameliorates D-galactose (D-gal)-induced cognitive dysfunction by restoring hippocampal energy metabolism and preserving synaptic integrity, along with exploring upstream signaling mechanisms. Methods EZP efficacy was evaluated in D-gal mice through behavioral tests (MWM and Y-maze) and hippocampal histology (H&E and Nissl staining). Untargeted metabolomics was used to identify EZP-responsive metabolic pathways. For pathway analyses, we examined synaptic proteins (PSD95, SYN), Tau phosphorylation, glycogen, lactate, ATP metabolism (including GS, GP, HK activity), and PI3K/AKT/GSK3β signaling by western blotting. GPR30 involvement was further probed using the selective antagonist G15. Results EZP markedly improved cognitive function, attenuated hippocampal neuronal damage, normalized neuronal morphology, and increased Nissl body counts in D-gal mice. Untargeted metabolomics revealed that EZP reversed key metabolites in glycolysis and the TCA cycle. GPR30 expression was also elevated by EZP. G15 co-administration largely attenuated these beneficial effects, as evidenced by deteriorated behavioral performance, aggravated neuronal damage, reduced synaptic protein expression, and enhanced Tau hyperphosphorylation. EZP replenished hippocampal glycogen, lactate, and ATP, restored GS and GP expression, without affecting HK activity. At the signaling level, EZP promoted PI3K and AKT phosphorylation and reduced GSK3β phosphorylation; these effects were reversed by G15. Conclusion Overall, these data provide correlative evidence that GPR30 signaling is permissive for EZP's effects on hippocampal energy metabolism and synaptic integrity, with GSK3β phosphorylation as a noted downstream event in this process.