Amino acid- and lipid-related metabolic remodeling in PTZ-kindled mice reveals candidate plasma signatures of chronic epilepsy.

Background: Metabolic dysfunction is increasingly implicated in epilepsy, but the systemic metabolic alterations associated with chronic seizures remain incompletely characterized. This study aimed to define peripheral metabolic signatures of chronic epilepsy in a pentylenetetrazol (PTZ)-kindled mouse model and to examine whether the altered pathways were supported by human epilepsy transcriptomic data. Methods: Male C57BL/6 mice were subjected to repeated PTZ injections to establish chronic epilepsy, while control mice received saline. Plasma samples were analyzed using ultra-high-performance liquid chromatography-mass spectrometry-based untargeted metabolomics. Differential metabolites were identified through multivariate and univariate analyses, followed by KEGG pathway enrichment. Least absolute shrinkage and selection operator (LASSO) regression was used as an exploratory feature-selection method. To provide complementary human hippocampal transcriptomic context, the hippocampal subset of GSE256068 was reanalyzed using differential expression analysis, and KEGG pathway enrichment analysis. Results: PTZ-kindled mice displayed a distinct plasma metabolic profile compared with controls. A total of 349 differential metabolites were identified, mainly enriched in amino acid metabolism, tryptophan metabolism, and central carbon metabolism. LASSO regression identified six candidate metabolic features, all of which are reported in the supplementary material. Among them, indolelactic acid (ILA) and DG (20:3n6/0:0/20:3n6) were prioritized for biological interpretation because of their relevance to tryptophan-related and lipid-related metabolism. Reanalysis of the human hippocampal transcriptomic dataset revealed pathway-level alterations related to GABAergic synaptic signaling, glycosphingolipid biosynthesis, inflammatory regulation of TRP channels, and inflammatory response, providing complementary human hippocampal context for the neurotransmitter-, lipid-, and inflammatory--related metabolic alterations observed in PTZ-kindled mice. Conclusion: PTZ-induced kindling was associated with marked plasma metabolic alterations involving amino acid-, tryptophan-, and lipid-related pathways. ILA and DG (20:3n6/0:0/20:3n6) emerged as candidate plasma metabolic features associated with the PTZ-kindled seizure phenotype. Complementary analysis of human temporal lobe epilepsy with hippocampal sclerosis (TLE-HS) hippocampal transcriptomic data identified related alterations in neurotransmission-, lipid-, and inflammatory-associated pathways. This pathway-level convergence supports the broader relevance of metabolic dysregulation to epilepsy, while the mechanistic roles and biomarker potential of individual metabolites require independent validation.