IDO Activation Affects BDNF/TrkB Signaling Pathway, Oxidative Stress, and Mitochondrial Enzymatic Activities in Temporal Lobe Epilepsy.

Indoleamine 2,3-dioxygenase (IDO) activation by seizures elevates toxic tryptophan metabolites linked to seizure exacerbation. Brain-derived neurotrophic factor (BDNF)/tyrosine kinase B (TrkB) signaling, oxidative stress, and mitochondrial respiratory chain complex dysfunction contribute to temporal lobe epilepsy (TLE), but their regulatory links remain unclear. Male Kunming mice were grouped into Control, Control + 1-Methyl-DL-tryptophan (1-MT), TLE, and TLE + 1-MT. TLE was induced with 300 mg/kg pilocarpine. Two weeks after modeling, 1-MT (50 mg/kg) was administered twice daily for two weeks in 1-MT groups. Assessments included video monitoring to record seizure frequency and duration; Nissl and Fluoro-Jade B (FJB) staining to evaluate neuronal damage; real-time quantitative PCR (qRT-PCR) and Western blot to detect IDO, BDNF, and TrkB expression; assays for the following oxidative stress markers: malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT); and detection of mitochondrial complex I/IV activities. Results showed TLE mice had significantly increased IDO expression, BDNF/TrkB over-activation, elevated oxidative stress, impaired mitochondrial complex I/IV activities, severe neuronal damage, and increased seizure frequency/duration. 1-MT intervention reversed all these pathological changes, restoring levels to near-control status. This indicates IDO activation promotes TLE progression, which is associated with modulation of the BDNF/TrkB signaling pathway, exacerbation of oxidative stress, and impairment of mitochondrial complex I/IV activities-supporting IDO as a potential therapeutic target for TLE.