The mechanism of potentiation of the glutamate-induced neurotoxicity by serum albumin. A possible role of nitric oxide.
Potentiation of the delayed (Glu)-induced neurotoxicity by serum albumin (SA) was studied in experiments with cultured cerebellar granule cells. The delayed neuronal death (DND) was evaluated by counting neurons containing or excluding Trypan Blue 4 h after treatment with Glu. Cytoplasmic Ca2+ ([Ca2+]i) was measured in individual Fura-2-loaded neurons. It was shown that a 15-min application of bovine SA (4 mg/ml) together with Glu (100 microM, 10 microM glycine, Mg2+-free solution) enhanced DND in the culture 1.7 times (43.1+/-3.1%) with respect to the effect induced by Glu alone (24.6+/-0.6%). The bovine SA application did not change the dynamics of [Ca2+]i response during a short-term (1 min) and long-term (15 min) Glu-treatment. DND was prevented by simultaneous application of Glu and inhibitor of NO-synthase N omega-nitro-L-arginine methyl ester (L-NAME), 100 microM) (10.8+/-1.0%) as well as by the application of Glu with SA and L-NAME (9.8+/-1.2%). In order to evaluate the role of nitric oxide (NO) in the SA effect, the cells were incubated for 15 min with the NO-donors sodium nitroprusside (SNP, 10 and 100 microM) and sodium nitrite (NaNO2, 10 and 100 microM) together with SA and in its absence. SA also greatly enhanced the DND induced by SNP and NaNO2. Thus, the DND after simultaneous treatment with SA and SNP was 16.3+/-2.5% (10 microM) or 29.6+/-2.1% (100 microM), and 9.6+/-0.8% (10 microM) and 19.7+/-2.1% after treatment with SNP alone. Exposure to SA together with NaNO2 led to the DND increase up to 26.5+/-1.9% (10 microM) and 37.7+/-3.5% (100 microM) in comparison with 7.4+/-2.0% (10 microM) and 18.9+/-0.8% (100 microM) in experiments with NaNO2 alone. Taking into account the ability of NO and NO2 to oxidize unsaturated fatty acids and the ability of SA to bind them after their hydrolytic removal, we suggested that the SA-induced potentiation of Glu neurotoxicity resulted from exacerbation of the toxic effects of NO and other trace radicals on the neuronal membranes. This hypothesis was supported by the finding that SA also enhanced the neurotoxicity of the lipid prooxidant FeCl2. The simultaneous 15-min application of FeCl2 (10 microM) and SA caused a 51.5+/-4.0% increase in DND, which exceeded 2.4 times the effect produced by FeCl2 alone (21.3+/-2.3%).
Sorokina
E G
EG
Institute of Pediatrics, Russian Academy of Medical Sciences, Moscow.
Reutov
V P
VP
Pinelis
V G
VG
Vinskaya
N P
NP
Vergun
O V
OV
Khodorov
B I
BI
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002452:Cell Count; D018929:Cell Culture Techniques; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004347:Drug Interactions / Q000502:physiology*; D005609:Free Radicals / Q000009:adverse effects / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism* / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D009498:Neurotoxins / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism*; D051381:Rats; D012709:Serum Albumin / Q000378:metabolism* / Q000494:pharmacology*; D013997:Time Factors
D005609:Free Radicals; D009498:Neurotoxins; D012709:Serum Albumin; D009569:Nitric Oxide; D018698:Glutamic Acid