Gentiopicroside protects against kainic acid-induced excitotoxicity by preserving glutamate homeostasis in rats.

This study provides the first evidence that gentiopicroside, a bioactive constituent isolated from Gentiana scabra, protects against kainic acid (KA)-induced excitotoxicity in rats. Intraperitoneal pretreatment with gentiopicroside (50 mg/kg) 30 min prior to KA administration (15 mg/kg) significantly mitigated seizure severity and prevented KA-induced cerebral blood flow (CBF) deficits. Histological analyses revealed that gentiopicroside markedly attenuated KA-induced neuronal loss, ultrastructural damage, and glial activation in the hippocampus. Mechanistically, gentiopicroside preserved the homeostasis of the glutamate-glutamine cycle, thereby reducing pathologically elevated hippocampal glutamate concentrations. This protective effect was mediated by the upregulation of glutamate transporter-1 (GLT-1) and glutamine synthetase (GS), alongside with the downregulation of glutamine transporters (SNAT1/3), glutaminase, and vesicular glutamate transporter 1 (VGLUT1). Furthermore, gentiopicroside normalized KA-induced alterations in AMPA and NMDA receptor subunit compositions, specifically restoring decreased GluA1, GluA2, and GluN2A levels while suppressing GluN2B upregulation. Additionally, gentiopicroside alleviated KA-induced mitochondrial dysfunction by suppressing calpain expression, restoring calpastatin and mitofusin 2 (MFN2) levels, and downregulating apoptotic protease activating factor 1 (Apaf-1). These findings suggest that gentiopicroside exhibits neuroprotective effects against KA-induced acute glutamate excitotoxicity by maintaining glutamate homeostasis, preventing calpain-mediated mitochondrial impairment, and attenuating glial neuroinflammation. These results highlight its therapeutic potential for excitotoxicity-related neurological disorders.