Related Experiment Video
Updated: Aug 14, 2026
Continuous Video Electroencephalogram during Hypoxia-Ischemia in Neonatal Mice
Published on: June 11, 2020
Perinatal seizures preferentially protect CA1 neurons from seizure-induced damage in prepubescent rats
1NJ Neuroscience Institute, Seton Hall University, South Orange, NJ 07079, USA.
Insights
Early seizures in neonatal rats do not advance the window of hippocampal vulnerability. Instead, repeated early seizures induce neuroprotection, altering neuronal properties in the hippocampus.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Epilepsy Research
Background:
- Neonatal seizures are a concern for long-term neuronal health.
- The timing of seizure-induced neuronal vulnerability is not fully understood.
Purpose of the Study:
- To investigate if early seizures shift the window of hippocampal vulnerability to a younger age.
- To examine the long-term effects of kainate-induced seizures on neuronal vulnerability and neuroprotection.
Main Methods:
- Status epilepticus was induced using kainate (KA) in rats at different postnatal ages (P13, P20, P30).
- Single (1x KA) and multiple (3x KA) injection paradigms were used, including early perinatal seizures (P6, P9).
- Electroencephalography (EEG), silver impregnation, hematoxylin/eosin, and TUNEL staining were employed to assess neuronal activity and damage.
Main Results:
- Single KA injections showed age-dependent seizure onset and EEG changes.
- Multiple KA injections in younger rats (P13) increased EEG activity, while older rats (P20, P30) showed decreased EEG parameters compared to single injections.
- Histological analysis revealed significant hippocampal injury in P20 and P30 rats after single KA injections, with notable protection in CA1 neurons after multiple KA injections.
Conclusions:
- Early perinatal seizures do not advance the critical window of hippocampal vulnerability.
- Repeated early seizures induce a form of tolerance leading to long-term neuroprotection.
- This neuroprotection differentially impacts CA1 and CA3 neuronal properties, suggesting complex adaptive mechanisms.
Abstract:
Neonatal seizures may increase neuronal vulnerability later in life. Therefore, status epilepticus was induced with kainate (KA) during the first and second postnatal (P) weeks to determine whether early seizures shift the window of neuronal vulnerability to a younger age. KA was injected (i.p.) once (1x KA) on P13, P20 or P30 or three times (3 x KA), once on P6 and P9, and then either on P13, P20 or P30. After 1x KA, onset to behavioral seizures increased with age. Electroencephalography (EEG) showed interictal events appeared with maturation. After 3 x KA, spike number, frequency, spike amplitude, and high-frequency synchronous events and duration were increased at P13 when compared to age-matched controls. In contrast, P20 and P30 rats had decreases in EEG parameters relative to P20 and P30 rats with 1x KA despite that these animals had the same history of perinatal seizures on P6 and P9. In P13 rats with 1x KA, silver impregnation, hematoxylin/eosin and TUNEL methods showed no significant hippocampal injury and damage was minimal with 3 x KA. In contrast, P20 and P30 rats with 1x KA had robust eosinophilic or TUNEL positive labeling and preferential accumulation of silver ions within inner layer CA1 neurons. After 3 x KA, the CA1 but not CA3 of P20 and P30 rats was preferentially protected following 3 or 6 days. Although paradoxical changes occur in the EEG with maturation, the results indicate that early perinatal seizures do not significantly shift the window of hippocampal vulnerability to an earlier age but induce a tolerance that leads to long-term neuroprotection that differentially affects endogenous properties of CA1 versus CA3 neurons.
