phosphorus-radioisotopes and Seizures

Kainic acid (KA) induces status epilepticus in both adult and young rats but with different consequences on pathology and gene expression. In adults, GluR2(B) AMPA subunit expression is markedly reduced in CA3 neurons before neurodegeneration. In pups, the GluR2(B) subunit is sustained, possibly contributing to neuronal survival. Mechanisms underlying the reduced vulnerability of developing neurons to seizures was investigated by examining the effects of unilateral microinfusions of GluR2(B) antisense oligodeoxynucleotides (AS-ODNs) into the hippocampus of young rats in the presence or absence of a subconvulsive dose of KA. GluR2(B) AS-ODN infusions resulted in spontaneous seizure-like behavior, high stimulus intensity population spikes in the absence of long-term potentiation, and neurodegeneration of CA3 neurons lateral to the infusion site. Electroencephalography revealed paroxysmal activity and high-frequency high-amplitude discharges associated with vigorous and continuous scratching, wild running, or bilateral jerking movements. Pups lacking phenotypic behavior exhibited high-rhythmic oscillations and status epilepticus by the dose of KA used. Radiolabeled AS-ODNs accumulated throughout the ipsilateral dorsal hippocampus. GluR2(B) but not GluR1(A) receptor protein was markedly reduced after GluR2(B) knockdown. In contrast, GluR1(A) knockdown reduced GluR1(A) but not GluR2(B) protein without change in behavior or morphology. Therefore, unilateral downregulation of hippocampal GluR2(B) but not GluR1(A) protein reduces the seizure threshold and survival of CA3 neurons in the immature hippocampus, possibly providing a novel partial seizure model in the developing rat.

Topics: Animals; Autoradiography; Electroencephalography; Epilepsies, Partial; Functional Laterality; Hippocampus; Infusions, Parenteral; Interleukin-11 Receptor alpha Subunit; Long-Term Potentiation; Male; Nerve Degeneration; Oligodeoxyribonucleotides, Antisense; Phosphorus Radioisotopes; Rats; Rats, Sprague-Dawley; Receptors, AMPA; Receptors, Interleukin; Receptors, Interleukin-11; Seizures

Picrotoxin administration decreased the incorporation of labelled phosphate in neurospecific protein synapsin I in vitro in cortex. In the animal hippocampus, the incorporation was more expressed. The data obtained suggest that activation of the cAMP-dependent phosphorylation occurs during seizure in the cortex.

Topics: Animals; Cerebral Cortex; Convulsants; Cyclic AMP; Hippocampus; Male; Phosphorus Radioisotopes; Phosphorylation; Picrotoxin; Rats; Rats, Wistar; Seizures; Synapsins; Synaptosomes

31P NMR studies on the brains of living rabbits were carried out at 32 MHz in a spectrometer having a 200-mm clear bore. Paralyzed pump-ventilated animals under nitrous oxide analgesia were inserted into the 1.89-T field and signals were focused in the brain by using a 4-cm surface coil. Several conventional physiological variables were monitored together with 31P spectra during induction and reversal of insulin shock and hypoxic hypoxia sufficient to abolish the electroencephalogram and during status epilepticus. A reversible decrease in phosphocreatine stores accompanied by an increase in Pi was detected during hypoglycemia and hypoxia. Similar changes were observed in prolonged status epilepticus but were not reversed. ATP levels fell about 50% in hypoglycemia but only slightly in the other two metabolic stresses. Intracellular pH rose in hypoglycemia; in status epilepticus and hypoxia it fell, but only when cardiovascular function was severely impaired. From the measured NMR parameters and the assumptions (i) that creatine kinase was at equilibrium and (ii) that the creatine/phosphocreatine pool was constant, it was possible to calculate the relative changes in cytoplasmic ADP levels associated with these metabolic disturbances.

Topics: Animals; Brain; Hypoglycemia; Hypoxia; Magnetic Resonance Spectroscopy; Mathematics; Phosphorus Radioisotopes; Rabbits; Seizures

A new method for measuring the uptake of materials labeled with radioactive phosphorus (32P) in the brain of a freely moving rat is described. The rate of uptake in the brain of a single animal of 32P-labeled phosphate was compared to the uptake rate in the animal's blood or liver. A comparison was made between the uptake following an intravenous (IV) or an intraperitoneal (IP) injection. The effect of convulsions caused by injections of metrazol on the kinetics of 32P uptake in the brain is described.

Topics: Animals; Brain; Injections, Intraperitoneal; Injections, Intravenous; Kinetics; Liver; Male; Pentylenetetrazole; Phosphorus; Phosphorus Radioisotopes; Rats; Scintillation Counting; Seizures

Topics: Adrenocorticotropic Hormone; Brain; Neurochemistry; Nucleoproteins; Phospholipids; Phosphorus; Phosphorus Compounds; Phosphorus Radioisotopes; Phosphorus, Dietary; Seizures