Integrated WGCNA and Network Pharmacology Explore the Potential Mechanisms of D-Limonene in Alleviating Traumatic Brain Injury

D-limonene (D-Lim) is a monocyclic monoterpene and the principal component of citrus essential oils; however, the potential mechanisms underlying its neuroprotective effects in traumatic brain injury (TBI) remain incompletely elucidated. By integrating network pharmacology, weighted gene co-expression network analysis (WGCNA), molecular docking, and experimental validation, this study systematically investigated the potential mechanisms through which D-Lim exerts neuroprotective activity. Database analyses and in vivo experiments showed that the anti-inflammatory and neuroprotective effects produced by D-Lim may be related to the p38 MAPK/NF-κB signaling axis and activation of the PI3K/AKT signaling pathway. Molecular docking and RT-PCR experiments indicated interactions between D-Lim and potential target proteins, including Icam1, Kdr, and Dpp4. HE and Nissl staining demonstrated that D-Lim ameliorated TBI-induced neuronal injury. Moreover, D-Lim had no observable effects on major organs and showed no peripheral toxicity, suggesting its favorable applicability for TBI intervention. Following early intervention with D-Lim, the inflammatory response induced by TBI was attenuated, which may be associated with the activation or modulation of the p38 MAPK, PI3K/AKT, and NF-κB p65 signaling pathways. These results indicate a potential acute protective role for D-Lim under prophylactic or early-intervention conditions, provide insights into TBI intervention, and establish a theoretical basis for potential preventive strategies.