Sulforaphane Ameliorates Metabolic Changes Associated With Status Epilepticus in Immature Rats

Abstract

Status epilepticus (SE) is a common paediatric emergency with the highest incidence in the neonatal period and is a well-known epileptogenic insult. As previously established in various experimental and human studies, SE induces long-term alterations to brain metabolism, alterations that directly contribute to the development of epilepsy. To influence these changes, organic isothiocyanate compound sulforaphane (SFN) has been used in the present study for its known effect of enhancing antioxidative, cytoprotective, and metabolic cellular properties via the Nrf2 pathway. We have explored the effect of SFN in a model of acquired epilepsy induced by Li-Cl pilocarpine in immature rats (12 days old). Energy metabolites PCr, ATP, glucose, glycogen, and lactate were determined by enzymatic fluorimetric methods during the acute phase of SE. Protein expression was evaluated by Western blot (WB) analysis. Neuronal death was scored on the FluoroJadeB stained brain sections harvested 24 h after SE. To assess the effect of SFN on glucose metabolism we have performed a series of 18F-DG μCT/PET recordings 1 h, 1 day, and 3 weeks after the induction of SE. Responses of cerebral blood flow (CBF) to electrical stimulation and their influence by SFN were evaluated by laser Doppler flowmetry (LDF). We have demonstrated that the Nrf2 pathway is upregulated in the CNS of immature rats after SFN treatment. In the animals that had undergone SE, SFN was responsible for lowering glucose uptake in most regions 1 h after the induction of SE. Moreover, SFN partially reversed hypometabolism observed after 24 h and achieved full reversal at approximately 3 weeks after SE. Since no difference in cell death was observed in SFN treated group, these changes cannot be attributed to differences in neurodegeneration. SFN per se did not affect the glucose uptake at any given time point suggesting that SFN improves endogenous CNS ability to adapt to the epileptogenic insult. Furthermore, we had discovered that SFN improves blood flow and accelerates CBF response to electrical stimulation. Our findings suggest that SFN improves metabolic changes induced by SE which have been identified during epileptogenesis in various animal models of acquired epilepsy.

Protective Effect of Sulforaphane on Oxidative Stress and Mitochondrial Dysfunction Associated with Status Epilepticus in Immature Rats

“…The important question arises whether the protective effect of SFN could not be due to an anticonvulsant effect. However, the behavior pattern of seizures (latency, severity, frequency, duration) was not influenced in our study by SFN and the absence of the anticonvulsant effect of SFN has also been confirmed by EEG recordings (see [62] Supplementary Fig. 1).…”

“…Interestingly, similar findings were found by Luis-Garcia et al [58]. These authors, using the rodent experimental model of Huntington's disease induced by quinolinic acid, reported that sulforaphane attenuated effectively mitochondrial dysfunction by preventing the decrease of respiratory control ratio, Table 1 Effect of SNF associated with Li-pilocarpine-induced SE in immature rats (information taken from [62])…”

“…Concerning glucose metabolism (measured by 18F-DGµCT/ PET recordings), SFN pretreatment not only reversed hypermetabolism in the acute phase, but it also improved hypometabolism, starting 1 day after SE (subacute phase) and lasting at least up to 22 days after onset of SE (latent phase). Importantly, SFN pretreatment led to a significantly increased expression of Nrf2 and Nrf2/ARE regulated enzyme SOD1 in the immature brain (detected by western blot analyses) (see also Table 1, summarizing the main findings of [62]).…”

“…We have therefore decided to explore the effect of SFN during status epilepticus (SE) induced in immature 12-day-old rats by Li-pilocarpine and to perform rather an extensive study concerning the effect of SFN pretreatment on EEG activity, cerebral blood flow (CBF), glucose metabolism, and energy metabolites (part I) and oxidative stress and mitochondrial dysfunction (part II). Findings of the part I have already been published [ 62 ].…”

Potential new roles for glycogen in epilepsy

“…In some cases, impaired energy metabolism may also contribute to or even cause epileptic seizures. 36,37 In rat chronic seizure models, the use of FDG and [ 14 C] DG also demonstrated decreases in glucose metabolism in brain areas presumed to be involved in seizure generation in several studies, 6,7,38,39 although others did not detect any significant differences, 40,41 which may be due to methodological detection limits. Importantly, several papers did not find correlations between the extent of hypometabolism and cell loss, indicating that, similar to data from people with epilepsy, hypometabolism is more widespread than the neuronal damage and occurs in remaining neurons and astrocytes.…”