Studies on the post-ictal rise in seizure threshold.
Seizure thresholds were determined by timed infusion of a convulsant drug. Following an electroconvulsive shock (ECS) rats exhibited a raised seizure threshold to infusion of the GABA antagonist drugs, pentylenetetrazol, bicuculline and isopropyl-bicyclophosphate, but not to the glycine antagonist strychnine or the 5-HT agonist, quipazine. The increase in threshold was seen following a bicuculline-induced seizure and 30 min following the last of a course of ECS given once daily for 10 days. The rise in seizure threshold still occurred when animals were pretreated with alpha-methyl-p-tyrosine (200 mg . kg-1), p-chlorophenylalanine (200 mg . kg-2), naloxone (1 mg . kg-1) or indomethacin (20 mg . kg-1). Diazepam (2 mg . kg-1), flurazepam (10 mg . kg-1) and sodium valproate (400 mg . kg-1) elevated basal seizure threshold and a further rise followed the ECS. Phenytoin (40 mg . kg-1) and carbamazepine (40 mg . kg-1) had no effect on basal seizure threshold or the ECS-induce rise. (¿Propranolol (20 mg . kg-1) did not affect basal seizure threshold but prevented the ECS-induced increase. The rise in seizure threshold following a convulsion may be an important adaptive mechanism which could be related to the reported increase in specific benzodiazepine binding following a seizure.
D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology; D001640:Bicuculline / Q000494:pharmacology; D001921:Brain / Q000378:metabolism; D003292:Convulsants / Q000494:pharmacology*; D004597:Electroshock; D018756:GABA Antagonists; D006221:Halothane / Q000494:pharmacology; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D008452:Maximum Allowable Concentration; D018377:Neurotransmitter Agents / Q000378:metabolism; D010433:Pentylenetetrazole / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011453:Prostaglandins / Q000096:biosynthesis; D051381:Rats; D012640:Seizures / Q000209:etiology*
D000927:Anticonvulsants; D003292:Convulsants; D018756:GABA Antagonists; D018377:Neurotransmitter Agents; D011453:Prostaglandins; D008012:Lidocaine; D011433:Propranolol; D006221:Halothane; D010433:Pentylenetetrazole; D001640:Bicuculline