Hippocampus-biased proteomic remodeling after multiple cerebral infarction: Mechanism of Rehmannia glutinosa extract

ABSTRACT: Rehmannia glutinosa extract has been widely used in the treatment of multiple cerebral infarction, but its neurorepair effects and associated molecular responses remain incompletely characterized. In this study, a rat multiple cerebral infarction model was established by microsphere-induced cerebral ischemia, followed by treatment with Rehmannia glutinosa extract. Neurological function, brain atrophy, neuronal integrity, and hippocampal neurogenic responses were evaluated. Label-free quantitative proteomics was performed separately in the ipsilateral cortex and hippocampus to characterize region-specific molecular responses to Rehmannia glutinosa extract, and proteins showing multiple cerebral infarction-associated alterations that changed in the opposite direction following Rehmannia glutinosa extract treatment were subjected to functional enrichment analysis. Catalpol, a representative constituent detected in Rehmannia glutinosa extract, was subsequently evaluated in oxygen-glucose deprivation/reoxygenation-injured PC12 cells, and the involvement of Hedgehog signaling was examined using cyclopamine, a smoothened inhibitor. Rehmannia glutinosa extract treatment improved neurological outcomes and reduced brain atrophy following multiple cerebral infarction, accompanied by preservation of neuronal integrity and enhanced early neurogenic responses in the hippocampal dentate gyrus. Proteomic profiling revealed distinct treatment-associated responses in the cortex and hippocampus. In the hippocampus, 102 multiple cerebral infarction-associated proteins exhibited opposite-direction changes following Rehmannia glutinosa extract treatment, with functional enrichment implicating injury and inflammatory responses, gliogenesis, cellular homeostasis, and synaptic-associated processes. In oxygen-glucose deprivation/reoxygenation-injured PC12 cells, catalpol improved cellular recovery and partially restored neuronal structural and repair-associated markers, including neurofilament light chain, whereas growth-associated protein 43 showed a non-significant recovery trend. Catalpol also modulated Hedgehog pathway-related proteins, and cyclopamine attenuated the catalpol-associated improvement in cell confluence, indicating an association between the cellular response to catalpol and Hedgehog pathway integrity. Collectively, these findings indicate that Rehmannia glutinosa extract promotes hippocampus-predominant proteomic remodeling after multiple cerebral infarction in model mice, accompanied by improved neurological function, attenuated brain atrophy, and enhanced hippocampal neurogenesis. Catalpol may participate in the remodeling-associated neural repair processes by modulating the Hedgehog pathway.