Increased hippocampal T2 in a rat model of pentylenetetrazol-induced kindling correlates with seizure scores

Background: Clinical and experimental magnetic resonance imaging (MRI) studies have demonstrated that epilepsy is associated with hippocampal atrophy and T-2-related abnormalities. The main aim of the present study is to investigate the mechanisms underlying regional T-2 changes in a rat model of pentylenetetrazol (PTZ)-kindling. Methods: Sprague-Dawley rats received 14 doses of PTZ or saline every second day, and their convulsant responses to each PTZ injection were scored. The animals were imaged 7-10 days after the final dose. Based on their seizure scores during treatment and in a screening test performed 2 weeks post-treatment, the PTZ-treated animals were retrospectively divided into the kindled group and the unkindled group. Selected animals were sacrificed for histology after the screening test. Results: Starting from the 8th injection, the average seizure score in kindled animals became significantly higher than that in unkindled animals. About half of the PTZ-treated rats developed hippocampal atrophy. Whether kindled or not, treated animals showed selective neuronal loss and astrocytosis in the hippocampus. No significant T-2 changes were observed for the unkindled rats, but T-2 was significantly elevated in the hippocampus and entorhinal cortex of the kindled animals. T-2 in the hippocampus and entorhinal cortex of the treated animals correlated positively with the sum of the seizure scores over the entire kindling period. Conclusions: Instead of being merely a manifestation of neuronal degeneration. T-2 increases in the hippocampus and EC of the PTZ-kindled animals may have reflected neurobiologic processes that are related to kindling epileptogenesis. (C) 2010 Elsevier B.V. All rights reserved.