The University of Georgia College of Veterinary Medicine

eorgia Veterinary Scholars Program

GVSP Summer 2008 Scholars

Georgia Veterinary Scholar	Faculty Mentor

Lauralyn Marshall University of Georgia Class of 2011	Dr. Cynthia Ward

The Effects of the Soy Isoflavone Biochanin A on Feline Hyperthyroid Cell Culture

Lauralyn Marshall*. Ward, Cynthia; Rupp, Nikki. University of Georgia College of Veterinary Medicine. Athens, GA.

Hyperthyroidism has recently become a commonly diagnosed disease in older cats. It is characterized by benign multinodular hyperplasia of the thyroid gland. The thyroid gland develops hyper functioning areas that produce excessive amounts of thyroid hormone in an unregulated fashion. The cause of feline
hyperthyroidism is not known, but previous studies suggest that there is a component in commercially available canned cat food that may be involved. As cats are obligate carnivores, the introduction of plant based food components to their daily diet may be part of the etiology of this disease. This project examines
the role of soy-based proteins, present in cat food, in the etiology of feline hyperthyroidism. We have treated a feline hyperthyroid cell line with five concentrations of a soy isoflavone, biochanin A, and TSH and lookedfor cellular activation similar to that seen in naturally occurring hyperthyroidism. Activation responses measured included mitosis and hormone (thyroglobulin) production using immunohistochemical staining. Cells treated with 1X10-3 M and 1X10-4 M biochanin A had the highest percentage of cells undergoing mitosis (47% ± 22 and 46 ± 33). The amount of mitosis occurring increased with increasing concentrations of biochanin A; however, two of the lowest concentrations, 1X10-6 M and 1X10-7 M biochanin A, caused an increase in mitosis (27% ± 5 and 26% ± 5) over 1X10-5 M biochanin A (21% ± 7). Thyroglobulin production decreased with decreasing concentrations of biochanin A (1X10-3 M,44% ± 16, 1X10-4M, 42% ± 8,
and 1X10-7M, 28% ± 4), but thyroglobulin production was highest in concentrations of 1X10-5 M and 1X10-6M biochanin A (51% ± 10 and 51% ± 16).

Research Support: Merck
Student Support: Dr. Cynthia Ward, Nikki Rupp

Research Support: Thank you to Merck and VMES for supporting GA Vet Sch Elijah Edmondson