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Electroconvulsive Seizures in Rats and Fractionation of Their Hippocampi to Examine Seizure-induced Changes in Postsynaptic Density Proteins
Published on: August 15, 2017
Early-life epileptiform discharges exert both rapid and long-lasting effects on AMPAR subunit composition and
Qian Jiang1, Jingmin Wang, Ye Wu
1Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
Insights
Early life seizures alter AMPA receptor (AMPAR) composition in developing neurons. This study shows increased GluR1 and decreased GluR2 on neuron surfaces after seizure-like events, impacting brain development.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Epilepsy Research
Background:
- The perinatal brain is vulnerable to epilepsy due to rapid developmental changes.
- Altered AMPA receptor (AMPAR) function is linked to seizure-induced brain damage and developmental impairments.
- The impact of early epileptiform discharges on AMPAR composition and localization is not well understood.
Purpose of the Study:
- To investigate the age-dependent changes in GluR1 and GluR2 AMPA receptor subunit levels in primary rat cortical neurons.
- To determine the effects of early-life seizure-like activity on AMPAR subunit composition and sub-cellular distribution.
Main Methods:
- Primary rat cortical neurons were cultured and analyzed at different developmental stages (7, 12, 17, 21 days in vitro).
- A single epileptiform activity event was induced at 6 days in vitro using magnesium-free medium.
- Western blotting and sub-cellular fractionation were used to quantify synaptosomal membrane levels of GluR1 and GluR2.
Main Results:
- Neurons exposed to seizure-like activity showed a significant, time-dependent increase in synaptosomal GluR1 expression.
- GluR2 expression initially increased at 7DIV but subsequently declined at 17DIV and 21DIV.
- A notable trend of higher GluR1 to GluR2 ratio was observed on the surface membrane of neurons experiencing epileptiform discharges.
Conclusions:
- Early-life seizure-like events induce lasting alterations in AMPAR composition at the neuronal surface.
- These changes in AMPAR subunit balance may contribute to the cellular mechanisms underlying epilepsy-associated brain dysfunction.
- Findings provide insights for rodent models of epilepsy and understanding developmental consequences of early seizures.
Abstract:
The perinatal period of brain is characterized by dynamic changes in structure and high propensity for epilepsy. Animal models have shown that alterations of AMPA receptor (AMPAR) assembly or function may be related to seizure-induced cell damage, long-lasting impairments in brain development and seizure threshold. However, effects of earlier epileptiform discharges on AMPAR composition and sub-cellular distribution remain understudied. In this study, we analyzed age-dependent variation of relative GluR1 and GluR2 protein levels in primary cultured rat cortical neurons at 7DIV, 12DIV, 17DIV and 21DIV. By inducing a single event of epileptiform activity at 6DIV, we tested the effects of early-life seizure-like insults on AMPAR subunit distribution. We found a significant increase in synaptosomal membrane GluR1 expression in magnesium-free (MGF) medium-treated neurons at each time point detected (p<0.05), while GluR2 expression increased at 7DIV, and declined at 17DIV and 21DIV respectively (p<0.05). That is, a trend of high GluR1 with much lower GluR2 expression on the surface membrane of epileptiform discharges experienced neurons over time in culture was presented. These findings in an in vitro model of early-life seizure may inform rodent models of epilepsy, as well as the cellular mechanism involved in epilepsy-associated brain dysfunction.
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