Release of arginine, glutamate and glutamine in the hippocampus of freely moving rats: Involvement of nitric oxide

Watts, J., Fowler, L.J., Whitton, P.S. and Pearce, B.R. (2005) Release of arginine, glutamate and glutamine in the hippocampus of freely moving rats: Involvement of nitric oxide. Brain Research Bulletin, 65 (6). pp. 521-528. 10.1016/j.brainresbull.2005.03.011.

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DOI: 10.1016/j.brainresbull.2005.03.011

Abstract

Using in vivo microdialysis, we have monitored the release of three amino acids (arginine, glutamate and glutamine) in the hippocampus of freelymovingrats in response to various drugs. In response to N-methyl-d-aspartate (NMDA) infusion, extracellular glutamate was increased, glutamine was decreased and arginine remained unchanged. By contrast, α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA) elicited an increase in arginine release but had no effect on either glutamate or glutamine. When S-nitroso-N-acetylpenicillamine (SNAP), a nitricoxide (NO) donor, was infused into the hippocampus, an increase in glutamate, a decrease in glutamine and no change in arginine were recorded. The effect of SNAP on extracellular glutamine levels was reversed by prior infusion of the guanylate cyclase inhibitor [1], [2] and [4] oxadiazolo[4,3-α]quinoxalin-1-one (ODQ), however its effect on glutamate release was unchanged. Interestingly, SNAP was found to promote the release of arginine in the presence of ODQ. We also assessed the effect of two nitricoxide synthase inhibitors, N-nitro-l-arginine methylester (l-NAME) and 7-nitroindazole (7-NI), on the release of these amino acids. l-NAME was found to increase arginine and glutamate levels but decrease those of glutamine. In contrast, 7-NI reduced the release of all three amino acids. The results presented here confirm some but not all of the findings previously obtained using in vitro preparations. In addition, they suggest that complex relationships exist between the release of these amino acids, and that endogenous NO plays an important role in regulating their release.

Item Type:Article
Uncontrolled Keywords:Arginine; Glutamate; Glutamine; Hippocampus; Microdialysis; Nitricoxide; Nitricoxide synthase
Departments, units and centres:Department of Pharmacology > Department of Pharmacology
ID Code:3090
Journal or Publication Title:Brain Research Bulletin
Deposited By:Library Staff
Deposited On:20 Apr 2012 15:33
Last Modified:20 Apr 2012 15:33

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