title: Lymphocyte infiltration of neocortex and hippocampus after a single brief seizure in mice.
abstract: Various immune responses have been described in epileptic patients and animal models of epilepsy, but immune responses in brain after a single seizure are poorly understood. We studied immune responses in brain after a single brief generalized tonic-clonic seizure in mice. C57bl/6 mice, either unanesthetized or anesthetized (pentobarbital, ethyl chloride) received either electrical (15-30 mA, 100 Hz, 1s) or sham stimulation (subcutaneous electrodes over frontal lobe, no current). Electrical stimulation of unanesthetized mice resulted in tonic-clonic convulsions with hind-limb extension (maximal seizure), tonic-clonic convulsions without hind-limb extension (submaximal seizure), or no seizure. In contrast, such stimulation of anesthetized mice did not result in seizure. Mice were killed at 1h-7 days after seizure. Brains or regions dissected from brain (neocortex, hippocampus, midbrain, cerebellum) of each group were pooled, single cell suspensions prepared, and cells separated according to density. CD4(+) (CD3(+)CD45(Hi)) and CD8(+) (CD3(+)CD45(Hi)) T cell and CD45R(+) (CD45(Hi)) B cell numbers were determined by flow cytometry. At 24h after a maximal seizure, CD4(+) and CD8(+) T cells and CD45R(+) B cells appeared in brain, reaching peak numbers at 48 h, but were no longer detected at 7days. CD4(+) T cells and CD45R(+) B cells were preferentially found in neocortex compared with hippocampus, whereas CD8(+) T cells were preferentially found in hippocampus at 24h after a maximal seizure. In contrast, virtually no lymphocytes were detected in brains of unstimulated or sham stimulated mice, unanesthetized stimulated mice after submaximal or no seizure, and anesthetized stimulated mice at 1 h-7 day. Neither Ly6-G+ neutrophils nor erythrocytes were detected in brains of any animals, nor was there any detectable increase of blood-brain barrier permeability by uptake of Evans Blue dye. The results indicate that lymphocyte entry into brain after a single brief seizure is due to a selective process of recruitment into cortical regions.
authors.affiliation: School of Graduate Studies, State University of New York Downstate Medical Center, Brooklyn, NY 11203, United States. JonathanISilverberg@gmail.com
authors.forename: J
authors.initials: J
authors.lastname: Silverberg
authors.forename: D
authors.initials: D
authors.lastname: Ginsburg
authors.forename: R
authors.initials: R
authors.lastname: Orman
authors.forename: V
authors.initials: V
authors.lastname: Amassian
authors.forename: H G
authors.initials: HG
authors.lastname: Durkin
authors.forename: M
authors.initials: M
authors.lastname: Stewart
mesh_terms: D000758:Anesthesia; D000818:Animals; D000911:Antibodies, Monoclonal; D001402:B-Lymphocytes / Q000502:physiology; D016516:CD4-CD8 Ratio; D002465:Cell Movement; D002531:Cerebellum / Q000473:pathology; D004396:Coloring Agents; D004567:Electrodes, Implanted; D004597:Electroshock; D004912:Erythrocytes / Q000502:physiology; D005070:Evans Blue; D005434:Flow Cytometry; D006624:Hippocampus / Q000276:immunology / Q000473:pathology*; D008214:Lymphocytes / Q000502:physiology*; D008297:Male; D008636:Mesencephalon / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D019579:Neocortex / Q000276:immunology / Q000473:pathology*; D020556:Neutrophil Infiltration / Q000502:physiology*; D012640:Seizures / Q000276:immunology / Q000473:pathology*
chemical_list: D000911:Antibodies, Monoclonal; D004396:Coloring Agents; D005070:Evans Blue