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Persistent physiological effects caused by a single pentylenetetrazol induced seizure in neonatal rats
Insights
Neonatal seizures induced by pentylenetetrazol (PTZ) in rats cause lasting changes in brain function. These long-term effects on neuronal excitability depend on the age at which the seizure occurs.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Epilepsy Research
Background:
- Neonatal seizures can have long-term consequences on brain development and function.
- Understanding the age-dependent effects of early-life seizures is crucial for predicting long-term neurological outcomes.
Purpose of the Study:
- To investigate the long-lasting physiological effects of a single pentylenetetrazol (PTZ)-induced seizure on hippocampal synaptic plasticity in rats.
- To determine if these effects are dependent on the age of the animal at the time of the seizure.
Main Methods:
- Induced seizures using pentylenetetrazol (PTZ) in 1-day-old and 21-day-old rats.
- Performed in vitro electrophysiological recordings in hippocampal slices from adult rats.
- Assessed paired-pulse facilitation (PPF) of population excitatory postsynaptic potentials (EPSPs) and spikes in CA1, CA3, and dentate gyrus (DG) regions.
Main Results:
- PTZ-induced seizures on day 1 significantly increased PPF in the CA1 region and dentate gyrus (DG).
- PTZ-induced seizures on day 21 decreased PPF in the CA1 region but had no significant effect in the DG.
- No significant differences in CA3 responses or basic stimulus-response properties were observed.
Conclusions:
- A single neonatal PTZ-induced seizure has enduring physiological consequences on hippocampal synaptic function.
- The long-lasting effects are age-dependent, highlighting critical developmental windows for seizure impact.
Abstract:
A single seizure was induced by pentylenetetrazol (PTZ; 150 mg/kg i.p.) in 1-day-old and 21-day-old rats; control littermates were given saline (i.p.) injections. In vitro recordings were made in hippocampal slices derived from adult (2-3.5-month-old) rats. The population responses in CA1, CA3 and dentate gyrus (DG) were recorded following double-pulse stimulation of Schaffer collateral (CA1 stratum radiatum, for CA1 and CA3 recordings) and perforant path (for DG recordings). Paired-pulse stimuli at an interpulse interval (IPI) of 10-200 ms and intensity of 1.5, 2 or 4 times the stimulus threshold were used. PTZ given on day 1 resulted in a highly significant increase in the paired-pulse facilitation (PPF) of the population EPSP, but not of the population spike, in CA1 at all stimulus intensities. In the DG, PPF of both the population EPSP and population spike was found at 1.5 x threshold intensity. PTZ given on day 21 decreased PPF of the population EPSP and spike in CA1 and had no significant effect in the DG. No significant difference was found in CA3 responses after seizures on day 1 or day 21. The slices from seized and control animals were not different in their stimulus thresholds or response to a single pulse. It is concluded that a single neonatal PTZ-induced seizure had long-lasting physiological consequences which depend on the age of seizure.(ABSTRACT TRUNCATED AT 250 WORDS)