Ketogenic diet improves cognitive impairment in rats with temporal lobe epilepsy by activating the Nrf2/HO-1/GPX4 signaling axis to inhibit ferroptosis.

A ketogenic diet (KD) has demonstrated significant therapeutic efficacy in drug-resistant epilepsy. The molecular mechanisms through which KDs exert therapeutic effects on temporal lobe epilepsy (TLE) are not yet fully understood. Recent studies suggest that ferroptosis, a cell death pathway driven by iron-dependent lipid peroxidation, plays a role in the pathophysiological progression of epilepsy. This research revealed that lithium-pilocarpine (LI-PILO)-induced status epilepticus in TLE models triggered pronounced ferroptosis in the rat hippocampus and that KDs inhibited neuronal ferroptosis in the hippocampus, as evidenced by elevated levels of the antioxidant factors, glutathione (GSH) and catalase (CAT), and decreased levels of 4-HNE, Fe2+ and the lipid peroxidation product malondialdehyde (MDA). We also observed ferroptosis-related mitochondrial abnormalities, including reduced mitochondrial volume, disrupted cristae, and the outright disappearance of cristae, in the epilepsy model group. These morphological alterations were markedly attenuated following KD intervention. Furthermore, KDs alleviated both neuronal loss and cognitive impairment in TLE rats. However, the neuroprotective effects of KDs were completely abolished by the ferroptosis inducer erastin. In addition, treatment with the ferroptosis inhibitor ferrostatin-1 (Fer-1) not only reduced hippocampal neuronal damage, as confirmed by Nissl staining and immunofluorescence but also improved cognitive performance in TLE rats, as evidenced by better outcomes in the Morris water maze and novel object recognition tests. With respect to the underlying mechanism, multiomics analysis revealed that KDs alter circulating metabolite profiles. Notably, we revealed that deoxycholyl-L-dopa may be a key metabolite for targeting Keap1, xCT and HO-1. Western blot and qPCR results revealed that KDs activated the Nrf2/HO-1/GPX4 signaling axis and upregulated the expressions of Nrf2, HO-1, FTH1, xCT and GPX4. Our findings identify ferroptosis inhibition as a mechanism underlying the efficacy of KDs in epilepsy.