Inflammatory cytokines and related genes are induced in the rat hippocampus by limbic status epilepticus

MG De Simoni, C Perego, T Ravizza… - European Journal of …, 2000 - Wiley Online Library
MG De Simoni, C Perego, T Ravizza, D Moneta, M Conti, F Marchesi, A De Luigi, S Garattini…
European Journal of Neuroscience, 2000Wiley Online Library
Limbic status epilepticus was induced in rats by unilateral 60‐min electrical stimulation of
the CA3 region of the ventral hippocampus. As assessed by RT‐PCR followed by Southern
blot analysis, transcripts of interleukin‐1β, interleukin‐6, interleukin‐1 receptor antagonist
and inducible nitric oxide synthase were significantly increased 2 h after status epilepticus in
the stimulated hippocampus. Induction was maximal at 6 h for interleukin‐1β (445%),
interleukin‐6 (405%) and tumour necrosis factor‐α (264%) and at 24 h for interleukin‐1 …
Abstract
Limbic status epilepticus was induced in rats by unilateral 60‐min electrical stimulation of the CA3 region of the ventral hippocampus. As assessed by RT‐PCR followed by Southern blot analysis, transcripts of interleukin‐1β, interleukin‐6, interleukin‐1 receptor antagonist and inducible nitric oxide synthase were significantly increased 2 h after status epilepticus in the stimulated hippocampus. Induction was maximal at 6 h for interleukin‐1β (445%), interleukin‐6 (405%) and tumour necrosis factor‐α (264%) and at 24 h for interleukin‐1 receptor antagonist (494%) and inducible nitric oxide synthase (432%). In rats with spontaneous seizures (60 days after status epilepticus), interleukin‐1β mRNA was still higher than controls (241%). Immunocytochemical staining of interleukin‐1β, interleukin‐6 and tumour necrosis factor‐α was enhanced in glia with a time‐course similar to that of the respective transcripts. Sixty days after status epilepticus, interleukin‐1β immunoreactivity was increased exclusively in neurons in one third of the animals. Multiple intracerebroventricular injections of interleukin‐1 receptor antagonist (0.5 μg/3 μL) significantly decreased the severity of behavioural convulsions during electrical stimulation and selectively reduced tumour necrosis factor‐α content in the hippocampus measured 18 h after status epilepticus. Thus, the induction of spontaneously recurring seizures in rats involves the activation of inflammatory cytokines and related pro‐ and anti‐inflammatory genes in the hippocampus. These changes may play an active role in hyperexcitability of the epileptic tissue.
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