strychnine and Epilepsies--Myoclonic

Bilateral inferior olive lesions, produced by systemic administration of the neurotoxin 3-acetylpyridine (3AP) produce a proconvulsant state specific for strychnine-induced seizures and myoclonus. We have proposed that these phenomena are mediated through increased excitation of cerebellar Purkinje cells, through activation of glutamate receptors, in response to climbing fiber deafferentation. An increase in quisqualic acid (QA)-displaceable [3H]AMPA [(RS)-alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid] binding in cerebella from inferior olive-lesioned rats was observed, but no difference in [3H]AMPA binding displaced by glutamate, kainic acid (KA) or glutamate diethylester (GDEE) was seen. The excitatory amino acid antagonists GDEE and MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclo-hepten-5,10 imine] were tested as anticonvulsants for strychnine-induced seizures in 3AP inferior olive-lesioned and control rats. Neither drug effected seizures in control rats, however, both GDEE and MK-801 produced a leftward shift in the strychnine-seizure dose-response curve in 3AP inferior olive-lesioned rats. GDEE also inhibited strychnine-induced myoclonus in the lesioned group, while MK-801 had no effect on myoclonus. The decreased threshold for strychnine-induced seizures and myoclonus in the 3AP-inferior olive-lesioned rats may be due to an increase in glutamate receptors as suggested by the [3H]AMPA binding data.

Topics: alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; Animals; Anticonvulsants; Dizocilpine Maleate; Epilepsies, Myoclonic; Glutamates; Ibotenic Acid; Male; Olivary Nucleus; Pyridines; Quisqualic Acid; Rats; Rats, Inbred Strains; Seizures; Strychnine; Tritium

Nonketotic hyperglycinemia was diagnosed in identical twins with lethargy and respiratory failure in the neonatal period. Therapy with strychnine (0.32 mg/kg/day) resulted in great reductions in CSF and plasma glycine levels and improvement in muscle tone, respiration, and ability to suck. Myoclonic seizures were partially controlled by therapy with clonazepam. Higher dosages of strychnine (up to 2.0 mg/kg/day) were needed to counteract the increased lethargy following administration of clonazepam. At 5 months of age, the twins' developmental performance remained below the 1-month level despite adequate somatic growth. The twins died suddenly of status epilepticus at 6 1/2 months of age.

Topics: Amino Acid Metabolism, Inborn Errors; Clonazepam; Diseases in Twins; Epilepsies, Myoclonic; Female; Glycine; Humans; Infant, Newborn; Male; Pregnancy; Strychnine; Twins, Monozygotic