Inhibition of the mammalian target of rapamycin blocks epilepsy progression in NS-Pten conditional knockout mice

Abstract

SUMMARY Purpose Increased activity of mTOR Complex 1 (mTORC1) has been demonstrated in cortical dysplasia and tuberous sclerosis complex, as well as in animal models of epilepsy. Recent studies in such models revealed that inhibiting mTORC1 with rapamycin effectively suppressed seizure activity. However, seizures can recur after treatment cessation, and continuous rapamycin exposure can adversely affect animal growth and health. Here, we evaluated the efficacy of an intermittent rapamycin treatment protocol on epilepsy progression using neuron subset-specific-Pten (NS-Pten) conditional knockout mice. Methods NS-Pten knockouts were treated with a single course of rapamycin during postnatal weeks four and five, or intermittently over a period of five months. Epileptiform activity was monitored using video-EEG recordings, and mossy fiber sprouting was evaluated using Timm staining. Survival and body weight were assessed in parallel. Key Findings NS-Pten knockouts treated with a single course of rapamycin had recurrence of epilepsy four to seven weeks after treatment ended. In contrast, epileptiform activity remained suppressed, and survival increased if knockout mice received additional rapamycin during weeks 10–11 and 16–17. Aberrant mossy fiber sprouting, present by four weeks of age and progressing in parallel with epileptiform activity, was also blocked by rapamycin. Significance These findings demonstrate that a single course of rapamycin treatment suppresses epileptiform activity and mossy fiber sprouting for several weeks before epilepsy recurs. However, additional intermittent treatments with rapamycin prevented this recurrence and enhanced survival without compromising growth. Thus, these studies add to the growing body of evidence implicating an important role for mTORC1 signaling in epilepsy.

CXCR4 Antagonist AMD3100 Suppresses the Long-Term Abnormal Structural Changes of Newborn Neurons in the Intraventricular Kainic Acid Model of Epilepsy

“…The brains were removed and fixed in 4 % paraformaldehyde overnight, then transferred to 0.1 M PBS containing 30 % sucrose. Coronal sections (30 μm) were stained in parallel with Timm stain solution (120 mL of 50 % gum arabic, 20 mL of 2 M citrate buffer, 60 mL of hydroquinone, and 1 mL of 17 % silver nitrate) in the dark at room temperature for 90 min [23,24]. Slides were washed, dehydrated, and sealed with a coverslip.…”

In vivo effects of bumetanide at brain concentrations incompatible with NKCC1 inhibition on newborn DGC structure and spontaneous EEG seizures following hypoxia-induced neonatal seizures

“…The brains were removed, fixed in 4% paraformaldehyde for 24 h, transferred to 0.1 M PBS containing 30% sucrose, and cut into 30 lm coronal sections. Sections from each treatment group were stained in parallel with Timm stain solution (120 ml of 50% gum arabic, 20 ml of 2 M citrate buffer, 60 ml of hydroquinone and 1 ml of 17% silver nitrate) in the dark at room temperature for 90 min (Sunnen et al, 2011;Chen et al, 2014). Slides were washed, dehydrated, and sealed with a coverslip.…”

Deconvoluting mTOR biology

“…In genetically engineered mice, Pten inactivation in neuroglial cells results in progressive seizures, which can be dramatically attenuated with rapamycin analog treatment. [52][53][54] Moreover, these Pten conditional knockout mice exhibit abnormal social for nerve sheath tumors and gliomas in individuals with NF1.…”