Sarcosine Remodels DNA Methylation-Linked Transcriptional Networks During Epileptogenesis in the Rat Rapid Hippocampal Kindling Model

DNA methylation is implicated in epileptogenesis. Sarcosine, a glycine transporter 1 (GlyT1) inhibitor and methyl donor, attenuates behavioral progression during rapid hippocampal kindling and alters hippocampal DNA methylation, but its locus-specific epigenetic effects remain poorly understood. Here, reduced representation bisulfite sequencing (RRBS) was combined with targeted gene expression analysis in the hippocampi of sarcosine-treated kindled rats. RRBS identified 563, 533, and 390 differentially methylated regions (DMRs), corresponding to 521, 499, and 374 DMR-associated genes, in vehicle-kindled versus sham (vKD vs. vSH), sarcosine-kindled versus sham (sKD vs. vSH), and sarcosine-kindled versus vehicle-kindled (sKD vs. vKD) comparisons, respectively. Pathway enrichment analysis identified 217 significantly affected pathways, including glutamatergic signaling, extracellular matrix (ECM) organization, chromatin regulation, axon guidance, and apoptotic processes. Eleven candidate genes involved in epigenetic regulation, excitatory neurotransmission, and ECM remodeling were selected for transcriptional validation. All 11 genes were significantly upregulated in kindled hippocampi, whereas sarcosine was associated with reduced expression relative to vehicle-kindled rats for eight genes (Hdac9, Fos, Smad7, Unc5a, Grik2, Gpr37l1, Cacna2d2, and Yy1). Collectively, these findings indicate that sarcosine remodels DNA methylation-associated transcriptional networks during rapid hippocampal kindling and support GlyT1 inhibition as a potential disease-modifying approach in experimental epileptogenesis.