The Effect of long-term rapamycin administration on intracellular calcium quantification and RhoA activity in kainic acid epilepsy model

Abstract

Abstract Epilepsy affects around 50 million people worldwide, with 30% of them being refractory epilepsy. This shows that there is still a need for novel anti-seizure medication that have different mechanisms. One of the most common types of refractory epilepsy is temporal lobe epilepsy. Among the several effects of seizures on neurons is an increase in intracellular Ca2+ and activation of RhoA. Rapamycin is mTORC1 inhibitor, but long-term exposure to rapamycin (>18 hours) could also inhibit mTORC2. RhoA signaling pathway is regulated through the mTORC2 pathway; thus we hypothesized that long-term exposure to rapamycin could inhibit intracellular Ca2+ and RhoA activity as one of the mTORC2 downstream proteins, in a temporal lobe epilepsy model. This study used organotypic hippocampal slice cultures (OHSC) which were exposed to 20 nM rapamycin treatment for 3, 5, 8, and 10 days after induction of epilepsy by 7 μM kainic acid administration for 48 hours. Intracellular calcium concentration was observed using CLSM and RhoA activity with western blot. The results obtained from this research were long-term administration of rapamycin can decrease intracellular calcium concentration and RhoA activity in OHSC models of epilepsy induced by kainic acid, with the most effective duration is 5 days of exposure to rapamycin.

Keywords

• Rapamycin
• Calcium
• RhoA activity
• Organotypic hippocampal slice culture
• Epilepsy
• Kainic acid