Antagonism by NG-nitro-L-arginine of L-glutamate-induced neurotoxicity in cultured neonatal rat cortical neurons. Prolonged application enhances neuroprotective efficacy.
The effects of NG-nitro-L-arginine on L-glutamate-induced neurotoxicity have been evaluated on primary cultures of neonatal rat cortical neurons. Treatment of cultures with increasing concentrations of L-glutamate during 5 min produced a delayed neuronal death, as measured by lactate dehydrogenase release in the medium 24 h later. Maximal toxicity was obtained with 500 microM of L-glutamate. Substantial nitric oxide synthase activity was detected in these cortical cultures. Nitric oxide synthase activity and cellular L-glutamate-induced cyclic guanosine 3',5'-monophosphate accumulation were totally inhibited by 100 microM NG-nitro-L-arginine. Addition of NG-nitro-L-arginine (100 microM) to the medium either 5 min prior to and during L-glutamate exposure (500 microM, 5 min) or for 24 h after L-glutamate exposure decreased the amino acid-induced neurotoxicity by 23% (not significant) and 43%, respectively. When added 5 min before L-glutamate and just after L-glutamate removal and kept in contact with neurons for the following 24 h, NG-nitro-L-arginine (100 microM) antagonized by 74% the L-glutamate-induced neurotoxicity. This effect was not reversed by a co-application of L-arginine (1 mM). The neuroprotective effect of NG-nitro-L-arginine was concentration-dependent, a half-maximal inhibition of L-glutamate-induced neurotoxicity being observed with the addition (before and after L-glutamate) of 4 microM of the drug. These results suggest that the neuroprotective effect of NG-nitro-L-arginine previously observed in vivo is exerted at the neuronal level.(ABSTRACT TRUNCATED AT 250 WORDS)
Vigé
X
X
Synthélabo Recherche (L.E.R.S.), Biology Department, Bagneaux, France.
Carreau
A
A
Scatton
B
B
Nowicki
J P
JP
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors; D000818:Animals; D000831:Animals, Newborn; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects*; D006152:Cyclic GMP / Q000378:metabolism; D016291:Dizocilpine Maleate / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates / Q000633:toxicity; D018698:Glutamic Acid; D009474:Neurons / Q000187:drug effects*; D009569:Nitric Oxide / Q000502:physiology; D019001:Nitric Oxide Synthase; D019335:Nitroarginine; D009599:Nitroprusside / Q000633:toxicity; D051381:Rats; D017207:Rats, Sprague-Dawley
D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates; D009599:Nitroprusside; D019335:Nitroarginine; D009569:Nitric Oxide; D018698:Glutamic Acid; D016291:Dizocilpine Maleate; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D006152:Cyclic GMP; D015056:1-Methyl-3-isobutylxanthine