Recurrent seizures and brain pathology after inhibition of glutamine synthetase in the hippocampus in rats.

Published

Journal Article

An excess of extracellular glutamate in the hippocampus has been linked to the generation of recurrent seizures and brain pathology in patients with medically intractable mesial temporal lobe epilepsy (MTLE). However, the mechanism which results in glutamate excess in MTLE remains unknown. We recently reported that the glutamate-metabolizing enzyme glutamine synthetase is deficient in the hippocampus in patients with MTLE, and we postulated that this deficiency is critically involved in the pathophysiology of the disease. To further explore the role of glutamine synthetase in MTLE we created a novel animal model of hippocampal glutamine synthetase deficiency by continuous (approximately 28 days) microinfusion of methionine sulfoximine (MSO: 0.625 to 2.5 microg/h) unilaterally into the hippocampus in rats. This treatment led to a deficiency in hippocampal glutamine synthetase activity by 82-97% versus saline. The majority (>95%) of the MSO-treated animals exhibited recurrent seizures that continued for several weeks. Some of the MSO-treated animals exhibited neuropathological features that were similar to mesial temporal sclerosis, such as hippocampal atrophy and patterned loss of hippocampal neurons. However, many MSO-treated animals displayed only minimal injury to the hippocampus, with no clear evidence of mesial temporal sclerosis. These findings support the hypothesis that a deficiency in hippocampal glutamine synthetase causes recurrent seizures, even in the absence of classical mesial temporal sclerosis, and that restoration of glutamine synthetase may represent a novel approach to therapeutic intervention in this disease.

Full Text

Cited Authors

  • Eid, T; Ghosh, A; Wang, Y; Beckström, H; Zaveri, HP; Lee, T-SW; Lai, JCK; Malthankar-Phatak, GH; de Lanerolle, NC

Published Date

  • August 2008

Published In

Volume / Issue

  • 131 / Pt 8

Start / End Page

  • 2061 - 2070

PubMed ID

  • 18669513

Pubmed Central ID

  • 18669513

Electronic International Standard Serial Number (EISSN)

  • 1460-2156

International Standard Serial Number (ISSN)

  • 0006-8950

Digital Object Identifier (DOI)

  • 10.1093/brain/awn133

Language

  • eng