Effects of induced hypo- and hyperthyroidism on immune function and plasma biochemistry in mallards (Anas platyrhynchos).
Hypo- or hyperthyroid states were induced in adult male mallards (Anas platyrhynchos) by subchronic exposure to daily injections of methimazole or a 9:1 ratio of thyroxine (T4): triiodothyronine (T3). The levels of T4 given were 0, 125, 250, or 500 micrograms/kg/day and for methimazole; 10 mg/kg/day for 22 or 21 days. Plasma T3 showed a lasting decrease with T4:T3 treatment, despite the attempt to maintain the normal T4:T3 ratio. Antibody formation to sheep red blood cells was decreased only at the 125 micrograms/kg/day dose of T4, and was unaffected by methimazole treatment. Natural killer cell activity to RP-9 tumor cells and macrophage phagocytosis of killed, opsonized Saccaromyces cereviseae were unaffected by treatment throughout the study. However, lectin-dependent cellular cytotoxic activity to RP-9 tumor cells was significantly decreased after 21 days of methimazole treatment, indicating that hypothyroidism may have an influence on cell-mediated immunity. Hypo- and hyperthyroid conditions had opposing effects on plasma cholesterol levels.
Fowles
J R
JR
Toxicology Program, Oregon State University, Corvallis 97331, USA. Berkeley.JFowles@hw1.cahwnet.gov
Fairbrother
A
A
Kerkvliet
N I
NI
D000818:Animals; D013956:Antithyroid Agents / Q000008:administration & dosage; D015415:Biomarkers / Q000097:blood*; D001774:Blood Chemical Analysis; D002784:Cholesterol / Q000097:blood; D003601:Cytotoxicity Tests, Immunologic; D004305:Dose-Response Relationship, Drug; D004372:Ducks / Q000276:immunology*; D006980:Hyperthyroidism / Q000139:chemically induced / Q000276:immunology / Q000503:physiopathology*; D007037:Hypothyroidism / Q000139:chemically induced / Q000276:immunology / Q000503:physiopathology*; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology*; D037102:Lectins; D007958:Leukocyte Count; D008297:Male; D008713:Methimazole / Q000008:administration & dosage; D010587:Phagocytosis / Q000276:immunology; D013963:Thyroid Hormones / Q000097:blood* / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000276:immunology
D013956:Antithyroid Agents; D015415:Biomarkers; D037102:Lectins; D013963:Thyroid Hormones; D008713:Methimazole; D002784:Cholesterol