Long-Term Effects of Pentylenetetrazol-Induced Kindling Seizures on Neuroinflammation: Immunohistochemical and EEG Analysis in Rats

Abstract

The present experimental study examines the effects of PTZ-induced kindling, a well-established and widely used animal model for studying epileptogenesis through the progressive induction of seizures. The novelty of this research lies in its descriptive analysis of the post-kindling phase, focusing on both brain activity and molecular changes. Twelve rats were subjected to a three-phase protocol: habituation, challenge (60 mg/kg), and kindling, which involved repeated administration of subconvulsive doses of PTZ (35 mg/kg). The control group received only saline injections. In the first month following kindling, a subset of animals was implanted with epidural electrodes to record brain activity through electroencephalograph (EEG). In the second month, another subset was used for molecular analyses using immunohistochemistry (IHC) and immunofluorescence (IF), with GFAP and NeuN serving as markers for astrocytes and mature neurons, respectively. These molecular assessments were repeated in the third month post-kindling. EEG recordings revealed interictal events during the first post-kindling month. In the second and third months, a significant increase in GFAP expression was observed in hippocampal regions (CA1, CA3, and dentate gyrus), while NeuN expression remained unchanged. These findings contribute to the characterization of the post-kindling phase and enhance the understanding of the PTZ model's underlying mechanisms and temporal progression.