Isoliquiritigenin as a Neuronal Radiation Mitigant: Mitigating Radiation-Induced Anhedonia Tendency Targeting Grik3/Grm8/Grin3a via Integrated Proteomics and AI-Driven Discovery

Background/Objectives: Radiotherapy can cause severe and irreversible brain damage, including cognitive impairment, increased dementia risk, debilitating depression, and other neuropsychiatric disorders. Current radioprotective drugs face limitations, such as single-target inefficacy or manufacturing hurdles. Isoliquiritigenin (ISL), a natural flavonoid derived from licorice root, exhibits broad bioactivities. It exhibits anti-inflammatory, anti-cancer, immunoregulatory, hepatoprotective, and cardioprotective activities. This study aimed to elucidate ISL’s neuronal radiation mitigation effects and key targets. Methods: In vitro and in vivo models of radiation-induced neuronal injury were established. ISL’s bioactivities were evaluated through cellular cytotoxicity assays, LDH release, ROS, ATP, glutamate, and GSH levels. In vivo, ISL’s radiation mitigation effect was evaluated with sucrose preference test, IL-β level, histopathological analysis, and Golgi-Cox staining analysis. Proteomics, pathway enrichment, and ensemble models (four machine learning models, weighted gene co-expression network, protein–protein interaction) identified core targets. Molecular docking and dynamic simulations validated ISL’s binding stability with key targets. Results: ISL attenuated radiation-induced cellular cytotoxicity, reduced LDH/ROS, restored ATP, elevated GSH, and mitigated glutamate accumulation. In rats, ISL alleviated anhedonia-like phenotypes and hippocampal synaptic loss. ISL also significantly suppressed radiation-induced neuroinflammation, as evidenced by reduced levels of the pro-inflammatory cytokine IL-1β. Proteomic analysis revealed that ISL’s main protective pathways included the synaptic vesicle cycle, glutamatergic synapse, MAPK signaling pathway, SNARE interactions in vesicular transport, insulin signaling pathway, and insulin secretion. Grm8, Grik3, and Grin3a were identified as key targets using the integrated models. The expression of these targets was upregulated post-radiation and restored by ISL. Molecular docking and dynamic simulations indicated that ISL showed stable binding to these receptors compared to native ligands. Conclusions: ISL demonstrates multi-scale radiation mitigation activities in vitro and in vivo by modulating synaptic and inflammatory pathways, with glutamate receptors as core targets. This work nominates ISL as an important natural product for mitigating radiotherapy-induced neural damage.