The amygdala is critical for seizure propagation from brainstem to forebrain

• Published in: Neuroscience Vol. 77; no. 4; pp. 975 - 984
• Main Authors: Hirsch, E, Danober, L, Simler, S, Pereira de Vasconcelos, A, Maton, B, Nehlig, A, Marescaux, C, Vergnes, M
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.04.1997; Elsevier
• Subjects: 2-deoxyglucose; Acoustic Stimulation; amygdala; Amygdala - drug effects; Amygdala - physiopathology; Anesthetics, Local - pharmacology; Animals; audiogenic seizures; Biological and medical sciences; Brain Stem - chemistry; Brain Stem - metabolism; Brain Stem - physiopathology; brainstem seizures; c-Fos; Carbon Radioisotopes; Deoxyglucose; Electric Stimulation; Electroencephalography; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Kindling, Neurologic - physiology; Lidocaine - pharmacology; limbic seizures; Male; Medical sciences; Nervous system (semeiology, syndromes); Neurology; Prosencephalon - chemistry; Prosencephalon - metabolism; Prosencephalon - physiopathology; Proto-Oncogene Proteins c-fos - metabolism; Rats; Rats, Wistar; Seizures - physiopathology; DAB, diaminobenzidine; brainstem seizures; amygdala; NE, non-epileptic rats; 2-deoxyglucose; GEPR, genetically epilepsy-prone rat; c-Fos; EEG, electroencephalogram; limbic seizures; audiogenic seizures; KAS, Rats with fully kindled audiogenic seizures; 2-DG, [ 14C]2-deoxyglucose; AS, audiogenic susceptible naı̈ve rats; Animal model; Nervous system diseases; Amygdala; Rat; Brain stem; Rodentia; Central nervous system; Basal ganglion; Cerebral disorder; Audiogenic epilepsy; Prosencephalon; Vertebrata; Mammalia; Central nervous system disease; Brain (vertebrata)
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(96)00503-9

Audiogenic seizures, a model of brainstem epilepsy, are characterized by a tonic phase (sustained muscular contraction fixing the limbs in a flexed or extended position) associated with a short cortical electroencephalogram flattening. When sound-susceptible rats are exposed to repeated acoustic stimulations, kindled audiogenic seizures, characterized by a clonic phase (facial and forelimb repetitive jerks) associated with cortical spike-waves, progressively appear, suggesting that repetition of brainstem seizures causes a propagation of the epileptic discharge toward the forebrain. In order to determine the structures through which this propagation occurs, four kinds of experiments were performed in non-epileptic rats and in sound-susceptible rats exposed to single or repeated sound stimulations. The following results were obtained: (1) Electrical amygdalar kindling was similar in non-epileptic and naı̈ve-susceptible rats, but was facilitated in sound-susceptible rats submitted to 40 acoustic stimulations and presenting kindled audiogenic seizures. (2) Audiogenic seizures induced an increase in [ 14C]2-deoxyglucose concentration in the amygdala after a single seizure, and in the amygdala, hippocampus and perirhinal and piriform cortices after a kindled audiogenic seizure. (3) A single audiogenic seizure induced the expression of c-Fos protein mainly in the auditory nuclei. A few cells were stained in the amygdala. After 5–10 audiogenic seizures, a clear staining appeared in the amygdala, and perirhinal and piriform cortices. The hippocampus expressed c-Fos later, after 40 audiogenic seizures. (4) Injection of lidocaine into the amygdala did not modify single audiogenic seizures, but suppressed myoclonias and cortical spike-waves of kindled audiogenic seizures. Similar deactivation of the hippocampus failed to modify kindled audiogenic seizures. Taken together, these data indicate a critical role for the amygdala in the spread of audiogenic seizures from brainstem to forebrain.