Structural changes in astrocytes induced by seizures in a model of temporal lobe epilepsy

Abstract

Injection of iron-chloride solution unilaterally into the hippocampus of albino rats induced transient seizure activity which lasted approximately 2 weeks. Frontal and parietal cortices of experimental rats, control rats which received NaCl injections, and unoperated normal rats were compared by means of a Golgi stain which demonstrated astrocytes and their processes in their entirety. Morphometric analysis showed that cortical astrocytes of rats having intermittent seizure activity over a prolonged period were significantly larger than cortical astrocytes of control rats. These findings indicate that seizure activity causes structural brain changes at anatomical sites distant from the hippocampal seizure focus. Similar phenomena may contribute to the development of psychiatric and neurological changes in the epileptic patient.

Loss of Astrocytic Domain Organization in the Epileptic Brain

“…Although the morphologic changes were significantly different from control animals, they were less pronounced than in the cortex of ferrous chloride-injected mice. The severity of reactive changes of astrocytes in kainateinjected mice is consistent with the notion that the seizure foci in kainate-injected animals reside in the CA3 hippocampal region (Castiglioni et al, 1990;Ben-Ari and Cossart, 2000).…”

“…8). Reactive changes of astrocytes in the opposite hemisphere were probably caused by projection of seizure discharge to this area (Castiglioni et al, 1990).…”

Hippocampal Sclerosis: Development in Adult Life

“…Hippocampal neuronal loss can be induced in animals by seizure activity or subconvulsive electrical stimulation in the amygdala, hippocampus and other structures [22][23][24], even in the absence of hypoxia [25][26][27][28]. This suggests that excitotoxicity is an important mechanism of the neuronal damage in the hippocampus.…”

Metabolism is Normal in Astrocytes in Chronically Epileptic Rats: A 13C NMR Study of Neuronal—Glial Interactions in a Model of Temporal Lobe Epilepsy

“…Studies on animal models of epilepsy show that gliosis is present in regions exhibiting epileptiform activity because of neuronal injury as well as seizure activity (Castiglioni et al, 1990;Eddleston and Mucke, 1993;Khurgel and Ivy, 1996). In Li-pilotreated rats, changes in astrocytes were mainly characterized by hypertrophy of cell bodies and processes near the lesions rather than an increase in astrocyte number (Roch et al, 2002).…”