Structure of thyroid and adrenal glands in rats fed diets of Great Lakes coho salmon ( Oncorhynchus kisutch)

Abstract

Feral Great Lakes coho salmon ( Oncorhynchus kisutch) were fed to Sprague-Dawley rats in order to determine the effects of bioaccumulated xenobiotics on mammalian endocrine physiology and assess the risk of human consumption of Great Lakes salmon. Rats fed coho salmon from Lakes Ontario, Erie, and Michigan had enlarged thyroid glands compared with controls fed Pacific Ocean coho or Rat Chow. The thyroid epithelial cell height was significantly increased in the rats fed Lake Ontario coho for 8 weeks, and the cells in this group, and to a lesser extent in the group fed Lake Michigan coho, contained more mitochondria, rough endoplasmic reticulum, Golgi profiles, and colloid-filled vacuoles than those of controls or rats fed Lake Erie coho. Dietary iodide supplementation to rats fed the Lake Ontario coho diet had no effect on either thyroid weight or thyroid histology, suggesting that the goiter was not due to iodide deficiency. The adrenal glands of rats fed coho from Lakes Erie or Michigan were significantly larger ( P < 0.01) than those in all other groups, apparently because of an enlargement of the zonae fasciculata and reticularis. In addition, rats given the Lake Ontario coho diet had markedly dilated sinusoidal spaces in the zonae fasciculata and reticularis of the adrenal cortex and also in the adrenal medulla.