Spontaneous seizures preferentially injure interneurons in the pilocarpine model of chronic spontaneous seizures. 1996

L E Mello, and L Covolan
Departamento de Fisiologia, Escola Paulista de Medicina-UNIFESP, São Paulo, Brazil.

It is still a question of much debate whether single epileptic seizures can cause cell loss. Despite the clinical impression that epilepsy in general is a progressive disorder, experimental evidence is not conclusive on this point. Recently, it has been shown that electrically-induced afterdischarges of less than 2 min may induce structural impairments in neurons. Here we evaluated whether spontaneous seizures would lead to similar impairments. Chronic spontaneous recurrent seizures were induced with pilocarpine (320 mg/kg, i.p.). Animals were sacrificed from 1 to 6 h either after single or multiple seizures. A Golgi-like sensitive silver-impregnation procedure was used to reveal injured neurons. Silver-impregnated dark neurons were never found in control animals nor in epileptic animals that had no behavioral seizures in the 8 h prior to sacrifice. After spontaneous seizures (injured) dark neurons were mostly interneurons and were present in hippocampus (CA1 stratum radiatum), amygdala, piriform cortex and other limbic structures. Animals with multiple seizures had a higher number of dark cells than animals with single seizures. Our findings suggest that even single generalized spontaneous tonic-clonic seizures can induce long-lasting morphological changes. Our results favor the idea that epilepsy is a progressive disorder where one seizure begets the next.

UI MeSH Term Description Entries
D007395 Interneurons Most generally any NEURONS which are not motor or sensory. Interneurons may also refer to neurons whose AXONS remain within a particular brain region in contrast to projection neurons, which have axons projecting to other brain regions. Intercalated Neurons,Intercalated Neuron,Interneuron,Neuron, Intercalated,Neurons, Intercalated
D008032 Limbic System A set of forebrain structures common to all mammals that is defined functionally and anatomically. It is implicated in the higher integration of visceral, olfactory, and somatic information as well as homeostatic responses including fundamental survival behaviors (feeding, mating, emotion). For most authors, it includes the AMYGDALA; EPITHALAMUS; GYRUS CINGULI; hippocampal formation (see HIPPOCAMPUS); HYPOTHALAMUS; PARAHIPPOCAMPAL GYRUS; SEPTAL NUCLEI; anterior nuclear group of thalamus, and portions of the basal ganglia. (Parent, Carpenter's Human Neuroanatomy, 9th ed, p744; NeuroNames, http://rprcsgi.rprc.washington.edu/neuronames/index.html (September 2, 1998)). Limbic Systems,System, Limbic,Systems, Limbic
D008297 Male Males
D010862 Pilocarpine A slowly hydrolyzed muscarinic agonist with no nicotinic effects. Pilocarpine is used as a miotic and in the treatment of glaucoma. Isopilocarpine,Isoptocarpine,Ocusert,Pilocarpine Hydrochloride,Pilocarpine Mononitrate, (3S-cis)-Isomer,Pilocarpine Nitrate,Pilocarpine, Monohydrochloride, (3S-cis)-Isomer,Salagen,Hydrochloride, Pilocarpine,Nitrate, Pilocarpine
D001921 Brain The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM. Encephalon
D004827 Epilepsy A disorder characterized by recurrent episodes of paroxysmal brain dysfunction due to a sudden, disorderly, and excessive neuronal discharge. Epilepsy classification systems are generally based upon: (1) clinical features of the seizure episodes (e.g., motor seizure), (2) etiology (e.g., post-traumatic), (3) anatomic site of seizure origin (e.g., frontal lobe seizure), (4) tendency to spread to other structures in the brain, and (5) temporal patterns (e.g., nocturnal epilepsy). (From Adams et al., Principles of Neurology, 6th ed, p313) Aura,Awakening Epilepsy,Seizure Disorder,Epilepsy, Cryptogenic,Auras,Cryptogenic Epilepsies,Cryptogenic Epilepsy,Epilepsies,Epilepsies, Cryptogenic,Epilepsy, Awakening,Seizure Disorders
D005260 Female Females
D006624 Hippocampus A curved elevation of GRAY MATTER extending the entire length of the floor of the TEMPORAL HORN of the LATERAL VENTRICLE (see also TEMPORAL LOBE). The hippocampus proper, subiculum, and DENTATE GYRUS constitute the hippocampal formation. Sometimes authors include the ENTORHINAL CORTEX in the hippocampal formation. Ammon Horn,Cornu Ammonis,Hippocampal Formation,Subiculum,Ammon's Horn,Hippocampus Proper,Ammons Horn,Formation, Hippocampal,Formations, Hippocampal,Hippocampal Formations,Hippocampus Propers,Horn, Ammon,Horn, Ammon's,Proper, Hippocampus,Propers, Hippocampus,Subiculums
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012640 Seizures Clinical or subclinical disturbances of cortical function due to a sudden, abnormal, excessive, and disorganized discharge of brain cells. Clinical manifestations include abnormal motor, sensory and psychic phenomena. Recurrent seizures are usually referred to as EPILEPSY or "seizure disorder." Absence Seizure,Absence Seizures,Atonic Absence Seizure,Atonic Seizure,Clonic Seizure,Complex Partial Seizure,Convulsion,Convulsions,Convulsive Seizure,Convulsive Seizures,Epileptic Seizure,Epileptic Seizures,Generalized Absence Seizure,Generalized Tonic-Clonic Seizures,Jacksonian Seizure,Myoclonic Seizure,Non-Epileptic Seizure,Nonepileptic Seizure,Partial Seizure,Seizure,Seizures, Convulsive,Seizures, Focal,Seizures, Generalized,Seizures, Motor,Seizures, Sensory,Tonic Clonic Seizure,Tonic Seizure,Tonic-Clonic Seizure,Atonic Absence Seizures,Atonic Seizures,Clonic Seizures,Complex Partial Seizures,Convulsion, Non-Epileptic,Generalized Absence Seizures,Myoclonic Seizures,Non-Epileptic Seizures,Nonepileptic Seizures,Partial Seizures,Petit Mal Convulsion,Seizures, Auditory,Seizures, Clonic,Seizures, Epileptic,Seizures, Gustatory,Seizures, Olfactory,Seizures, Somatosensory,Seizures, Tonic,Seizures, Tonic-Clonic,Seizures, Vertiginous,Seizures, Vestibular,Seizures, Visual,Single Seizure,Tonic Seizures,Tonic-Clonic Seizures,Absence Seizure, Atonic,Absence Seizure, Generalized,Absence Seizures, Atonic,Absence Seizures, Generalized,Auditory Seizure,Auditory Seizures,Clonic Seizure, Tonic,Clonic Seizures, Tonic,Convulsion, Non Epileptic,Convulsion, Petit Mal,Convulsions, Non-Epileptic,Focal Seizure,Focal Seizures,Generalized Seizure,Generalized Seizures,Generalized Tonic Clonic Seizures,Generalized Tonic-Clonic Seizure,Gustatory Seizure,Gustatory Seizures,Motor Seizure,Motor Seizures,Non Epileptic Seizure,Non Epileptic Seizures,Non-Epileptic Convulsion,Non-Epileptic Convulsions,Olfactory Seizure,Olfactory Seizures,Partial Seizure, Complex,Partial Seizures, Complex,Seizure, Absence,Seizure, Atonic,Seizure, Atonic Absence,Seizure, Auditory,Seizure, Clonic,Seizure, Complex Partial,Seizure, Convulsive,Seizure, Epileptic,Seizure, Focal,Seizure, Generalized,Seizure, Generalized Absence,Seizure, Generalized Tonic-Clonic,Seizure, Gustatory,Seizure, Jacksonian,Seizure, Motor,Seizure, Myoclonic,Seizure, Non-Epileptic,Seizure, Nonepileptic,Seizure, Olfactory,Seizure, Partial,Seizure, Sensory,Seizure, Single,Seizure, Somatosensory,Seizure, Tonic,Seizure, Tonic Clonic,Seizure, Tonic-Clonic,Seizure, Vertiginous,Seizure, Vestibular,Seizure, Visual,Seizures, Generalized Tonic-Clonic,Seizures, Nonepileptic,Sensory Seizure,Sensory Seizures,Single Seizures,Somatosensory Seizure,Somatosensory Seizures,Tonic Clonic Seizures,Tonic-Clonic Seizure, Generalized,Tonic-Clonic Seizures, Generalized,Vertiginous Seizure,Vertiginous Seizures,Vestibular Seizure,Vestibular Seizures,Visual Seizure,Visual Seizures

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