Abstract
The role of phospholipase C in the molecular mechanism of glutamate neurotoxicity was assessed in primary cultures of cerebellar neurons. It is shown that 1-[6-[[(17b)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino] hexyl]-1H-pyrrole-2,5-dione (U-73122) and 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphorylcholine (Et-18-OCH3), two agents that inhibit phospholipase C, prevent glutamate and N-methyl-d-aspartic acid (NMDA) neurotoxicity. It is shown that both compounds prevent glutamate neurotoxicity at concentrations lower than those required to inhibit carbachol-induced hydrolysis of inositol phospholipids. In contrast, it was a good correlation between the concentrations of U-73122 and Et-18-OCH3 required to inhibit NMDA-induced hydrolysis of phospholipids and those required to prevent glutamate and NMDA neurotoxicity. NMDA-induced hydrolysis of phospholipids is inhibited by nitroarginine, an inhibitor of nitric-oxide synthase, and is mimicked by the nitric oxide-generating agentS-nitroso-N-acetylpenicillamine. The results reported indicate that glutamate neurotoxicity would be mediated by activation of NMDA receptors, leading to activation of nitric-oxide synthase and increased formation of nitric oxide, which results in increased activity of phospholipase C. Inhibition of phospholipase C by U-73122 or Et-18-OCH3 prevents glutamate-induced neuronal death.
Footnotes
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Send reprint requests to: Vicente Felipo, Laboratory of Neurobiology, Instituto de Investigaciones Citologicas, FVIB, Amadeo de Saboya, 4, 46010 Valencia, Spain. E-mail:vfelipo{at}ochoa.fib.es
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1 This work was supported in part by grants from the Plan Nacional de Investigación y Desarrollo (SAF97-0001 and PM98-0065) of the Ministerio de Educación y Cultura of Spain and of Fundació La Marató de TV3. M.L. and P.M. are fellows of Conselleria de Educación de la Generalitat Valenciana.
- Abbreviations:
- mGluR
- metabotropic glutamate receptor
- AMPA
- (S)-α-amino-2,3-dihydro-5-methyl-3-oxo-4-isoxazolepropanoic acid
- ET-18-OCH3
- 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphorylcholine
- MCPG
- (±)-α-methyl-4-carboxyphenylglycine
- MK-801
- (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d]cyclohepten-5,10-imine hydrogen maleate
- NMDA
- N-methyl-d-aspartic acid
- NO
- nitric oxide
- NOS
- nitric-oxide synthase
- ODQ
- 1H-[1,2,4]oxadiaxolo[4,3-a]quinoxalin-1-one
- SNAP
- S-nitroso-N-acetyl-penicillamine
- tACPD
- trans-(±)-1-amino-1,3-cyclopentanedicarboxylic acid
- U-73122
- 1-[6-[[(17b)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione
- DNQX
- 6,7-dinitroquinoxaline-2,3-[1H,4H]-dione
- Received October 20, 1999.
- Accepted December 6, 1999.
- The American Society for Pharmacology and Experimental Therapeutics
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