Pentylenetetrazole decreases metabolic glutamate turnover in rat brain.
Seizures were induced in rats by intraperitoneal injection of pentylenetetrazole (PTZ, 70 mg/kg), followed, 30 min later, by injection of [1-13C]glucose and [1,2-13C]acetate. Analyses of extracts from cortex, subcortex and cerebellum were performed using 13C magnetic resonance spectroscopy and HPLC. It could be shown that PTZ affected different brain regions differently. The total amounts of glutamate, glutamine, GABA, aspartate and taurine were decreased in the cerebellum and unchanged in the other brain regions. GABAergic neurones in the cortex and subcortex were not affected, whereas those in the cerebellum showed a pronounced decrease of GABA synthesis. However, glutamatergic neurones in all brain regions showed a decrease in glutamate labelling and in addition a decreased turnover in cerebellum. It could be shown that this decrease was in the metabolic pool of glutamate whereas release of glutamate was unaffected since glutamine labelling from glutamate was unchanged. Aspartate turnover was also decreased in all brain regions. Changes in astrocyte metabolism were not detected, indicating that PTZ had no effect on astrocyte metabolism in the early postictal stage.
Eloqayli
Haytham
H
Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway.
Dahl
Carl Bredo
CB
Götestam
K Gunnar
KG
Unsgård
Geirmund
G
Hadidi
Hakam
H
Sonnewald
Ursula
U
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism*; D001923:Brain Chemistry / Q000187:drug effects; D002247:Carbon Isotopes; D002531:Cerebellum / Q000737:chemistry / Q000187:drug effects; D002540:Cerebral Cortex / Q000737:chemistry / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D005947:Glucose / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D010433:Pentylenetetrazole / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012640:Seizures / Q000139:chemically induced / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000032:analysis
D002247:Carbon Isotopes; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D005947:Glucose; D010433:Pentylenetetrazole