title: Neurotoxicity and immunotoxicity assessment in CBA/J mice with chronic Toxoplasma gondii infection and multiple oral exposures to methylmercury.
abstract: The present study was conducted to determine the effect of multiple low doses of methylmercury (MeHg) on the course of a chronic Toxoplasma gondii infection. Four groups of 6-wk-old female CBA/J mice either were fed 25 T. gondii tissue cysts of the ME-49 strain or were vehicle control. Six weeks later, half of each group was orally gavaged with 8-mg/kg body weight doses of MeHg on days 0, 2, 4, 7, 10, and 13, totaling 4 experimental groups. Mice were killed on day 17 or 18 after MeHg exposure. Flow cytometric analysis of lymphocyte subpopulations in the thymus demonstrated a significant increase in the percentage of CD4- CD8+ T-cells in mice exposed to MeHg with a concurrent T. gondii infection. Groups of mice exposed to MeHg showed a decrease in total thymic cellularity and cellularity of all T-cell subpopulations when compared with control mice, but viability of these cells was unaffected. Splenic cell viability was decreased in mice exposed to MeHg, but alterations in T-cell subpopulations were not noted. These data indicate that multiple low doses of MeHg may not exacerbate chronic toxoplasmosis, but MeHg-induced effects on the immune system were evident.
authors.affiliation: Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors.forename: Marquea D
authors.initials: MD
authors.lastname: King
authors.forename: David S
authors.initials: DS
authors.lastname: Lindsay
authors.forename: S
authors.initials: S
authors.lastname: Holladay
authors.forename: M
authors.initials: M
authors.lastname: Ehrich
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism / Q000469:parasitology; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002908:Chronic Disease; D005260:Female; D005434:Flow Cytometry; D007111:Immunity, Cellular / Q000187:drug effects; D000922:Immunotoxins / Q000493:pharmacokinetics / Q000633:toxicity*; D020287:In Situ Nick-End Labeling; D007668:Kidney / Q000378:metabolism; D008767:Methylmercury Compounds / Q000493:pharmacokinetics / Q000633:toxicity*; D051379:Mice; D008808:Mice, Inbred CBA; D009498:Neurotoxins / Q000493:pharmacokinetics / Q000633:toxicity*; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000187:drug effects; D013950:Thymus Gland / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D014124:Toxoplasmosis, Animal / Q000378:metabolism* / Q000473:pathology
chemical_list: D000922:Immunotoxins; D008767:Methylmercury Compounds; D009498:Neurotoxins; C004925:methylmercuric chloride