Prevention of glutamate neurotoxicity in cultured neurons by 3,4-dihydro-6-hydroxy-7-methoxy-2,2-dimethyl-1(2H)-benzopyran (CR-6), a scavenger of nitric oxide.
Glutamate neurotoxicity in cerebellar neurons in culture is mediated by excessive production of nitric oxide (NO). We anticipated that 3,4-dihydro-6-hydroxy-7-methoxy-2,2-dimethyl-1(2H)-benzopyran (CR-6) could act as a scavenger of NO since it contains a position (C-5) highly activated towards nitration reaction. The aim of this work was to assess whether CR-6 acts as an NO scavenger and prevents glutamate neurotoxicity in cultures of cerebellar neurons. It was shown that CR-6 reduced, in a dose-dependent manner, glutamate-induced formation of cGMP (EC50 approximately 15 microM) and prevented glutamate neurotoxicity. The protection was approximately 50% at 3-10 microM and nearly complete at 100 microM. CR-6 did not prevent glutamate-induced activation of NO synthase, but interfered with the glutamate-NO-cGMP pathway at a later step. CR-6 reduced the formation of cGMP induced by S-nitroso-N-acetylpenicillamine (SNAP), an NO-generating agent, indicating that CR-6 acts as a scavenger of NO in cultured neurons. This was further supported by experiments showing that in neurons treated with CR-6 and glutamate, the 5-nitro derivative of CR-6 was formed, as determined by GC-MS analyses. Moreover, in vitro incubation of CR-6 with SNAP also produced the 5-nitroderivative, thus confirming that CR-6 directly reacts with NO. The results reported indicate that CR-6 acts as an NO scavenger in neurons and prevents glutamate neurotoxicity.
Montoliu
C
C
Instituto de Investigaciones Citologicas de la Fundación Valenciana de Investigaciones Biomedicas, Spain.
Llansola
M
M
Sáez
R
R
Yenes
S
S
Messeguer
A
A
Felipo
V
V
D000818:Animals; D001578:Benzopyrans / Q000138:chemical synthesis / Q000494:pharmacology*; D002478:Cells, Cultured; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000138:chemical synthesis / Q000494:pharmacology*; D018698:Glutamic Acid / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D020011:Protective Agents / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D001578:Benzopyrans; C120400:CR 6; D018691:Excitatory Amino Acid Antagonists; D016166:Free Radical Scavengers; D020011:Protective Agents; D009569:Nitric Oxide; D018698:Glutamic Acid; D019001:Nitric Oxide Synthase