Anterior nucleus of thalamus stimulation inhibited abnormal mossy fiber sprouting in kainic acid-induced epileptic rats

•The latency time is prolonged and the spontaneously seizure is reduced after ANT-DBS in amygdala KA injection epilepsy model.•The abnormal mossy fiber sprouting is suppressed by the ANT-DBS.•A down-regulation of GAP-43 and up-regulation of Sema-3A expression in hippocampus formation is found after ANT-DBS. Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) has demonstrated antiepileptic efficacy, especially for mesial temporal lobe epilepsy (MTLE). Mossy fiber sprouting (MFS) is involved in the pathogenesis of MTLE, and Sema-3A and GAP-43 are pivotal regulators of MFS. This study investigated the effects of ANT-DBS on MFS and expression levels of Sema-3A and GAP-43 as a possible mechanism for seizure suppression. Adult male Sprague-Dawley rats were randomly divided into four groups: (1) control (saline injection), (2) KA (kainic acid injection), (3) KA + Sham-DBS (electrode implantation without stimulation), and (4) KA + DBS (electrode implantation with stimulation). Video electroencephalography (EEG) was used to ensure model establishment and monitor seizure frequency, latency, and severity (Racine stage). Chronic ANT stimulation was conducted for 35 days in the KA + DBS group, and MFS compared to the other groups by quantitative Timm staining. Sema-3A and GAP-43 expression levels in the hippocampal formation were evaluated in all groups with western blot. The latency period was significantly prolonged and spontaneous seizure frequency reduced in the KA + DBS group compared to KA and KA + Sham-DBS groups. Staining scores for MFS in CA3 and dentate gyrus (DG) were significantly lower in the KA + DBS group. The KA + DBS group also exhibited decreased GAP-43 expression and increased Sema-3A expression compared to KA and KA + Sham-DBS groups. These results suggest that ANT-DBS extends the latent period following epileptogenic stimulation by impeding MFS through modulation of GAP-43 and Sema-3A expression.