Modulation of absence seizures by branched-chain amino acids: correlation with brain amino acid concentrations.
The occurrence of absence seizures might be due to a disturbance of the balance between excitatory and inhibitory neurotransmissions in the thalamo-cortical loop. In this study, we explored the consequences of buffering the glutamate content of brain cells on the occurrence and duration of seizures in Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a genetic model of generalized non-convulsive epilepsy. Branched-chain amino acids (BCAAs) and alpha-ketoisocaproate (alpha-KIC), the ketoacid of leucine were repeatedly shown to have a critical role in brain glutamate metabolism. Thus, GAERS were injected by intraperitoneal (i.p.) or intracerebroventricular (i.c.v.) route with these compounds, then the effects on seizures were evaluated on the electroencephalographic recording. We also measured the concentration of amino acids in thalamus and cortex after an i.p. injection of leucine or alpha-KIC. Intracerebroventricular injections of leucine or alpha-KIC did not influence the occurrence of seizures, possibly because the substances reached only the cortex. BCAAs and alpha-KIC, injected intraperitoneally, increased the number of seizures whereas they had only a slight effect on their duration. Leucine and alpha-KIC decreased the concentration of glutamate in thalamus and cortex without affecting GABA concentrations. Thus, BCAAs and alpha-KIC, by decreasing the effects of glutamatergic neurotransmission could facilitate those of GABAergic neurotransmission, which is known to increase the occurrence of seizures in GAERS.
Dufour
F
F
INSERM U 398, Faculté de Médecine, 11 rue Humann, 67085 Strasbourg cédex, France.
Nalecz
K A
KA
Nalecz
M J
MJ
Nehlig
A
A
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000596:Amino Acids / Q000494:pharmacology; D000597:Amino Acids, Branched-Chain / Q000378:metabolism* / Q000494:pharmacology*; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects / Q000235:genetics; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D004569:Electroencephalography / Q000187:drug effects; D004573:Electrolytes; D004832:Epilepsy, Absence / Q000151:congenital / Q000188:drug therapy* / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology; D018698:Glutamic Acid / Q000187:drug effects / Q000378:metabolism; D007274:Injections, Intraperitoneal; D007276:Injections, Intraventricular; D007651:Keto Acids / Q000494:pharmacology; D007930:Leucine / Q000494:pharmacology; D008297:Male; D009434:Neural Pathways / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D057947:Parenteral Nutrition Solutions; D051381:Rats; D011919:Rats, Inbred Strains; D012996:Solutions; D013788:Thalamus / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology
D000596:Amino Acids; D000597:Amino Acids, Branched-Chain; D004573:Electrolytes; D007651:Keto Acids; D057947:Parenteral Nutrition Solutions; D012996:Solutions; C545824:amino-acid, glucose, and electrolyte solution; D018698:Glutamic Acid; C013082:alpha-ketoisocaproic acid; D007930:Leucine; D005947:Glucose