New pathway offers hope for untreatable seizures in rare genetic disorder

Tuberous sclerosis complex (TSC) is a neurodevelopmental disorder with epileptic seizures caused by genetic mutations in either TSC1 or TSC2 gene. Multiple genetic, epigenetic, and environmental factors can affect the phenotypical outcomes of TSC individuals. Accumulating evidence has shown that the seizures occurred in early life may contribute to the epileptogenesis and aggravate the neurological setting and neuropsychiatric symptoms of TSC. Therefore, treatments targeting seizures and/or epileptogenesis have always been the main focus on TSC therapies. Current anti-epileptic drugs and mTOR inhibitors show some efficacy, yet up to one-third of TSC-epileptic individuals are classified as refractory epilepsy. Vigabatrin, which has been used as the first-line therapy for infantile spasms in TSC, has demonstrated to delay the onset and lower the overall incidence of seizures in infants with TSC when it was used as a preventive treatment. Recently, because of its efficacy, cannabidiol, which targets adenosine signaling pathway, has been approved by the U.S. FDA for the treatment of TSC-associated epilepsy, suggesting an anti-epilepsy strategy other than mTOR inhibition is also plausible for TSC. To this end, we sought for a preventative treatment of an adenosine pathway-targeted therapeutic strategy. In this study, we pretreated Tsc2+/- mice with J4, an equilibrative nucleoside transporter 1 inhibitor, before the initiation of kindling epileptogenesis driven by the repetitive PTZ induction paradigm. We found that J4 reduced the seizure behavior severity in Tsc2+/- mice, as well as decreased mossy fiber sprouting resulted from the aberrant neurogenesis upon PTZ injurious insults. We also found that J4 increased the expression of GluR2, inhibited the astrogliosis and microgliosis, and eventually prevented the neuronal cell loss due to the excitotoxicity. The present study provides a new alternative therapeutic concept for pretreating TSC-related epilepsy before the epileptogenesis process.