Role of docosahexaenoic acid in modulating methylmercury-induced neurotoxicity.
The effect of docosahexaenoic acid (DHA) in modulating methylmercury (MeHg)-induced neurotoxicity was investigated in C6-glial and B35-neuronal cell lines. Gas chromatography measurements indicated increased DHA content in both the cell lines after 24 h supplementation. Mitochondrial activity evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyltetrazolium bromide (MTT) reduction indicated that 10 microM MeHg treatment for 50 min led to a significant (p < 0.001) and similar decrease in MTT activity in both the cell lines. However, DHA pretreatment led to more pronounced depletion (p < 0.05) in the MTT activity in C6 cells as compared to B35 cells. The depletion of glutathione (GSH) content measured with the fluorescent indicator monochlorobimane was more apparent (p < 0.001) in C6 cells treated with DHA and MeHg. The amount of reactive oxygen species (ROS) detected with the fluorescent indicator -- chloromethyl derivative of dichloro dihydro fluorescein diacetate (CMH(2)DCFDA) -- indicated a fourfold increase in C6 cells (p < 0.001) as compared to twofold increase in B35 cells (p < 0.001) upon DHA and MeHg exposure. However, the cell-associated MeHg measurement using (14)C-labeled MeHg indicated a decrease (p < 0.05) in MeHg accumulation upon DHA exposure in both the cell lines. These findings provide experimental evidence that although pretreatment with DHA reduces cell-associated MeHg, it causes an increased ROS (p < 0.001) and GSH depletion (p < 0.05) in C6 cells.
Kaur
Parvinder
P
Department of Neuroscience, Norwegian University of Science and Technology, N-7489, Trondheim, Norway. parvinder.kaur@ntnu.no
Schulz
Kristina
K
Aschner
Michael
M
Syversen
Tore
T
D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002849:Chromatography, Gas; D004396:Coloring Agents / Q000378:metabolism; D017077:Culture Media, Conditioned / Q000737:chemistry; D004281:Docosahexaenoic Acids / Q000032:analysis / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005978:Glutathione / Q000378:metabolism; D008767:Methylmercury Compounds / Q000378:metabolism / Q000633:toxicity*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009457:Neuroglia / Q000187:drug effects* / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts / Q000378:metabolism; D013844:Thiazoles / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*
D004396:Coloring Agents; D017077:Culture Media, Conditioned; D008767:Methylmercury Compounds; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; D014874:Water Pollutants, Chemical; D004281:Docosahexaenoic Acids; C022616:thiazolyl blue; D005978:Glutathione; C004925:methylmercuric chloride