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

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-1beta, 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-1beta (445%), interleukin-6 (405%) and tumour necrosis factor-alpha (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-1beta mRNA was still higher than controls (241%). Immunocytochemical staining of interleukin-1beta, interleukin-6 and tumour necrosis factor-alpha was enhanced in glia with a time-course similar to that of the respective transcripts. Sixty days after status epilepticus, interleukin-1beta immunoreactivity was increased exclusively in neurons in one third of the animals. Multiple intracerebroventricular injections of interleukin-1 receptor antagonist (0.5 microg/3 microL) significantly decreased the severity of behavioural convulsions during electrical stimulation and selectively reduced tumour necrosis factor-alpha 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.

The Rai (Shc C) adaptor protein regulates the neuronal stress response and protects against cerebral ischemia

“…RNA was isolated from lesioned side cortex according to the acid guanidium-phenol-chloroform method shown in ref. 20 and reverse-transcribed into cDNA. Primers were designed by using PRIMER EXPRESS software (Applied Biosystems) based on the following GenBank accession numbers: NM007393 (␤-actin), NM007527 (Bax), and NM009810 (procaspase-3).…”

Inflammation and epilepsy

“…The increase in messenger RNA (mRNA) expression and protein levels of proinflammatory cytokines after induction of seizures is rapid (≤30 min) and reversible, except for IL-1β, which is still upregulated 60 days after induction of status epilepticus in brain of rats developing spontaneous seizures; cytokines increase specifically in brain regions involved in seizure onset and spread (1,14,15). Evidence of increased production of inflammatory molecules in brain also has been reported in genetic models of audiogenic seizures and in kindling (16,17).…”

Expression of apoptosis inhibitor protein Mcl1 linked to neuroprotection in CNS neurons

“…41,42 Mcl1 is upregulated by cytokines such as interleukin-6 (IL6) acting through the JAK/ STAT pathway and interferon alpha, [43][44][45][46] by activin via the TGFb pathway 47 and by MEK, implicating the Ras/MEK/ MAPK pathway in Mcl1 transcription. 48 Since activity within these linked pathways increases rapidly in CNS ischemia and epilepsy, [49][50][51] the elevated transcription of Mcl1 may depend on the participation of a wide range of early inflammatory response signaling in the brain. The prompt elevation of Mcl1 expression in both mouse strains after SE suggests that the protein is involved in the earliest response to cell injury, and that upstream regulation is not differentially impaired in the two strains studied.…”