Oxidative stress and apoptotic changes in murine splenocytes exposed to cadmium.
Cadmium being a potent immunotoxicant, affects both humoral and cell mediated immunity. However, its effect on spleen is not clearly understood. Hence, to delineate the action of Cd, mouse splenic lymphocytes were exposed to Cd (10, 25 and 50 microM) for 60 min, 1.5, 3, 6 and 18 h. At 6 h, apoptosis was reflected by DNA fragmentation, increased sub-G1 population (apoptotic DNA) and apoptotic cells (Annexin V binding assay). The early stage markers of apoptosis, i.e. decreased mitochondrial membrane potential and caspase-3 activation were observed as early as 1.5 h by the highest dose of Cd (50 microM). Significant ROS production by 25 and 50 microM Cd at 60 min occurred prior to the lowering of mitochondrial membrane potential, suggesting involvement of ROS in causing mitochondrial membrane damage. N-acetylcysteine and pyrrolidine dithiocarbamate (thiol antioxidants) lowered the sub-G(1) population, inhibited the ROS generation and raised the GSH levels induced by Cd. Buthionine sulfoximine (GSH depletor) on the other hand, enhanced the ROS production as well as the sub-G1 fraction. These results imply that ROS is a critical mediator of Cd-induced apoptosis and that cadmium may compromise splenic immune function by accelerating apoptosis.
Pathak
Neelima
N
Industrial Toxicology Research Centre, P.O. Box 80, Mahatma Gandhi Marg, Lucknow 226001, India.
Khandelwal
Shashi
S
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002104:Cadmium / Q000633:toxicity*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004785:Environmental Pollutants / Q000633:toxicity*; D016193:G1 Phase / Q000187:drug effects; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000502:physiology; D009336:Necrosis; D018384:Oxidative Stress / Q000187:drug effects*; D011759:Pyrrolidines / Q000494:pharmacology; D013154:Spleen / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D013859:Thiocarbamates / Q000494:pharmacology
D004338:Drug Combinations; D004785:Environmental Pollutants; D011759:Pyrrolidines; D013859:Thiocarbamates; D002104:Cadmium; C020972:pyrrolidine dithiocarbamic acid; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D000111:Acetylcysteine