title: Spinal seizures evoked by sudden cooling of amphibian isolated spinal cords: involvement of excitatory amino acids.
abstract: Sudden cooling of the isolated spinal cord of frogs results in characteristic seizure-like activity in the hind legs. In the present investigation, these spinal seizures induced by sudden cooling (SSSC) were studied to determine whether excitatory amino acids (EAAs) are involved in the mediation of this activity. The nonspecific EAA antagonist, L-glutamic acid diethyl ester and cis-2,3-piperidine dicarboxylic acid inhibited the clonic and tonic phase of SSSC after intralymphatic or intrathecal administration. The antagonist gamma-D-glutamylaminomethylsulfonic acid and gamma-D-glutamyltaurine also suppressed both phases after intrathecal injections. The NMDA receptor antagonist DL-2-amino-5-phosphonovaleric acid, DL-2-amino-7-phosphonoheptanoic acid, and 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid were effective inhibitors of the tonic phase and actually prolonged the duration of the clonic phase, an effect similar to that observed after low doses of gamma-D-glutamylglycine. SSSC were resistant to spinal perfusion to tetrodotoxin (1 microM). The concentrations of glutamate, aspartate, and glycine were increased in the Ringer's solution surrounding rapidly cooled spinal cord slices, but only in cords from species that elicited some magnitude of SSSC, not in cords from species resistant to induction of SSSC. Our data support the hypothesis that EAAs play a role in SSSC via activation of quisqualate receptors.
authors.affiliation: Universidad Centro Occidental, Escuela de Ciencias Veterinarias, Barquisimeto, Venezuela.
authors.forename: N L
authors.initials: NL
authors.lastname: Daló
authors.forename: A A
authors.initials: AA
authors.lastname: Larson
mesh_terms: D000596:Amino Acids / Q000502:physiology*; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology; D001001:Anura; D003080:Cold Temperature / Q000009:adverse effects*; D004151:Dipeptides / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D010875:Pipecolic Acids / Q000494:pharmacology; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology; D012640:Seizures / Q000209:etiology* / Q000517:prevention & control; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D000927:Anticonvulsants; D004151:Dipeptides; D005971:Glutamates; D010875:Pipecolic Acids; D016194:Receptors, N-Methyl-D-Aspartate; C011829:glutamic acid diethyl ester; C028929:gamma-glutamylglycine; D013779:Tetrodotoxin; C029262:2,3-piperidinedicarboxylic acid