Increase of adenine nucleotide hydrolysis in rat hippocampal slices after seizures induced by quinolinic acid.
Quinolinic acid (QUIN), an endogenous convulsant compound, overstimulates the glutamatergic system stimulating N-methyl-D-aspartate receptors, enhancing glutamate release and inhibiting glutamate uptake. Glutamate releases the neuroprotector adenosine, which in turn reduces glutamate release and depresses the neuronal activity. Additionally, adenine nucleotides are an important source of adenosine, by action of ecto-nucleotidases. Here we evaluated the adenine nucleotide hydrolysis in hippocampal slices of adult rats in different times after seizures induced by QUIN. After 45 min, there was an increase of ATP and ADP hydrolysis. After 5 h, there was an increase of ATP, ADP and AMP hydrolysis. After 12 h, there was an increase only of ATP hydrolysis. After 24 h, all hydrolysis returned to control levels. As slice preparations maintain tissue integrity, this study indicates, more than previously observed with synaptosomal preparations, that the extracellular production of the neuroprotector adenosine may be involved in brain responses to seizures.
Nicolaidis
Rafael
R
Department of Biochemistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil. ranicolai@cpovo.net
Bruno
Alessandra Nejar
AN
Sarkis
João José Freitas
JJ
Souza
Diogo Onofre
DO
D000227:Adenine Nucleotides / Q000378:metabolism*; D000818:Animals; D003292:Convulsants / Q000008:administration & dosage; D006624:Hippocampus / Q000201:enzymology / Q000378:metabolism*; D006868:Hydrolysis; D066298:In Vitro Techniques; D007276:Injections, Intraventricular; D017378:Quinolinic Acid / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D017470:Receptors, Glutamate / Q000502:physiology; D011983:Receptors, Purinergic / Q000502:physiology; D012640:Seizures / Q000139:chemically induced* / Q000201:enzymology / Q000378:metabolism*
D000227:Adenine Nucleotides; D003292:Convulsants; D017470:Receptors, Glutamate; D011983:Receptors, Purinergic; D017378:Quinolinic Acid