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Delayed Impairment of Hippocampal Synaptic Plasticity after Pentylenetetrazole-Induced Seizures in Young Rats
Tatyana Y Postnikova1, Alina M Trofimova1, Maria V Zakharova1
1Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS, Saint Petersburg 194223, Russia.
Insights
Infant seizures can cause lasting brain damage, including neuronal loss and impaired synaptic plasticity in the hippocampus. This study reveals altered NMDA receptor function and glutamate transport following seizures in young rats.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Epilepsy Research
Background:
- Long-term consequences of infant seizures are not well understood.
- Generalized seizures in early life may impact brain development and function.
Purpose of the Study:
- To investigate the long-term effects of generalized seizures on the infant rat brain.
- To examine neuronal loss, synaptic plasticity, and receptor function after early-life seizures.
Main Methods:
- Induced generalized seizures using pentylenetetrazole in three-week-old rats.
- Assessed hippocampal neuronal loss, long-term potentiation (LTP), and NMDA receptor function one month post-seizure.
- Investigated the role of metabotropic glutamate receptors (mGluR1) and astrocytic glutamate transporter EAAT2.
Main Results:
- Moderate neuronal loss observed in hippocampal CA1, CA3, and hilus regions.
- Impaired long-term potentiation (LTP) and altered plasticity induction mechanisms.
- Evidence suggests increased perisynaptic NMDA receptor involvement and impaired glutamate clearance due to altered EAAT2 distribution.
Conclusions:
- Early-life generalized seizures lead to significant long-term hippocampal damage and functional deficits.
- Altered NMDA receptor function and impaired glutamate homeostasis contribute to post-seizure neurological consequences.
- Findings highlight potential therapeutic targets for mitigating seizure-induced brain injury in infants.
Abstract:
Data on the long-term consequences of a single episode of generalized seizures in infants are inconsistent. In this study, we examined the effects of pentylenetetrazole-induced generalized seizures in three-week-old rats. One month after the seizures, we detected a moderate neuronal loss in several hippocampal regions: CA1, CA3, and hilus, but not in the dentate gyrus. In addition, long-term synaptic potentiation (LTP) was impaired. We also found that the mechanism of plasticity induction was altered: additional activation of metabotropic glutamate receptors (mGluR1) is required for LTP induction in experimental rats. This disturbance of the plasticity induction mechanism is likely due to the greater involvement of perisynaptic NMDA receptors compared to receptors located in the core part of the postsynaptic density. This hypothesis is supported by experiments with selective blockades of core-located NMDA receptors by the use-dependent blocker MK-801. MK-801 had no effect on LTP induction in experimental rats and suppressed LTP in control animals. The weakening of the function of core-located NMDA receptors may be due to the disturbed clearance of glutamate from the synaptic cleft since the distribution of the astrocytic glutamate transporter EAAT2 in experimental animals was found to be altered.
