Status epilepticus induces time-dependent neuronal and astrocytic expression of interleukin-1 receptor type I in the rat limbic system.
Interleukin-1beta is rapidly synthesized by glia after the induction of seizures. Recent evidence shows that endogenous IL-1beta has proconvulsant actions mediated by interleukin-1 receptor type I. This receptor also mediates interleukin-1beta effects on neuronal susceptibility to neurotoxic insults. In this study, we investigated the basal and seizure-induced expression of interleukin-1 receptor type I in rat forebrain to identify the cells targeted by interleukin-1beta during epileptic activity. Self-sustained limbic status epilepticus was induced in rats by electrical stimulation of the ventral hippocampus. Interleukin-1 receptor type I immunoreactivity was barely detectable in neurons in control brain tissue. During status epilepticus, interleukin-1 receptor type I was induced in the hippocampal neurons firstly, and several hours later in astrocytes localized in limbic and extralimbic areas. Neuronal interleukin-1 receptor type I expression in the hippocampus outlasted the duration of spontaneous electroencephalographic seizure and was not observed in degenerating neurons. Astrocytic expression occurred transiently, between six and 18 h after the induction of status epilepticus and was invariably found in regions of neuronal damage. These time-dependent, cell- and region-specific changes in interleukin-1 receptor type I expression during status epilepticus suggest that interleukin-1 receptor type I in neurons mediates interleukin-1beta-induced fast changes in hippocampal excitability while interleukin-1 receptor type I receptors in astrocytes may mediate interleukin-1beta effects on neuronal survival in hostile conditions.
Ravizza
T
T
Laboratory of Experimental Neurology, Department of Neuroscience, Mario Negri Institute for Pharmacological Research, Via Eritrea 62, 20157 Milano, Italy. ravizza@marionegri.it
Vezzani
A
A
D000818:Animals; D001253:Astrocytes / Q000378:metabolism* / Q000473:pathology; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008032:Limbic System / Q000378:metabolism*; D008297:Male; D018613:Microscopy, Confocal; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017472:Receptors, Interleukin-1 / Q000096:biosynthesis*; D013226:Status Epilepticus / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D013997:Time Factors; D015854:Up-Regulation
D017472:Receptors, Interleukin-1