Modulation of innate and acquired immunity by an estrogenic dose of genistein in gonadectomized cats.
Dietary genistein has potential as a surrogate estrogen to restore normal control of food intake in cats following gonadectomy. However, since genistein affects immunological responses in other species it is important to determine if there is any immunological effect of genistein in cats, before long-term feeding of it could be considered. It was hypothesized that the minimum estrogenic dose of genistein (peak serum concentration 0.276+/-0.055 microg/mL) would be associated with altered innate and acquired immunity in cats. Cats (n=8 per group) were surgically neutered then treated daily with either 0.5 microg estradiol subcutaneously, 100mg/kg genistein orally, or vehicle only for 38 days. Circulating CD4+ and CD8+ T cells, and CD21+ B cells were quantified using flow cytometry. Concanavalin-A induced lymphocyte proliferation was assayed using incorporation of tritiated thymidine. Indirect ELISA was used to assay serum IgG in response to a commercial vaccine. Neutrophil respiratory burst in response to opsonized zymosan was evaluated using flow cytometric detection of oxidized dihydrorhodamine. Delayed-type hypersensitivity was evaluated with formalin-killed Yersinia pseudotuberculosis. Genistein treatment decreased circulating CD8+ cells (P=0.006), increased neutrophil respiratory burst (P=0.034), and increased wheal formation at 24h (P=0.038) but decreased wheal formation at 72 h (P=0.012) following intradermal challenge with killed Y. pseudotuberculosis. There were no significant differences between genistein treated cats and the other treatment groups in any other parameters. It is concluded that the minimum estrogenic dose of genistein alters selected leukocyte responses in cats. Unexpected effects of genistein suggest that extrapolation from one species to other species may not be appropriate in regards to the effects of genistein on immunity.
Cave
Nicholas J
NJ
Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand. n.j.cave@massey.ac.nz <n.j.cave@massey.ac.nz>
Backus
Robert C
RC
Marks
Stanley L
SL
Klasing
Kirk C
KC
D000818:Animals; D001772:Blood Cell Count / Q000662:veterinary; D015704:CD4 Antigens / Q000097:blood; D002369:Castration / Q000662:veterinary*; D002415:Cats / Q000276:immunology*; D004435:Eating / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005434:Flow Cytometry / Q000662:veterinary; D019833:Genistein / Q000494:pharmacology*; D006400:Hematocrit / Q000662:veterinary; D006968:Hypersensitivity, Delayed / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood; D008213:Lymphocyte Activation / Q000187:drug effects; D016131:Lymphocyte Subsets / Q000187:drug effects / Q000276:immunology; D008297:Male; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology; D048789:Phytoestrogens / Q000494:pharmacology*; D011897:Random Allocation; D017464:Receptors, Complement 3d / Q000097:blood; D016897:Respiratory Burst / Q000187:drug effects / Q000276:immunology; D015054:Zymosan / Q000276:immunology
D015704:CD4 Antigens; D007074:Immunoglobulin G; D048789:Phytoestrogens; D017464:Receptors, Complement 3d; D004958:Estradiol; D015054:Zymosan; D019833:Genistein