Zinc deficiency, chronic starvation, and hypothalamic-pituitary-thyroid function
1980
Morley, John E. | Gordon, Jody | Hershman, Jerome M.
Growth and thyroid hormone levels were measured in zinc-deficient, food-restricted and control-fed rats to compare the effects of zinc deficiency and chronic starvation on hypothalamic, pituitary and thyroid function. Growth was significantly impaired in both zinc-deficient and starved animals, as compared to controls allowed to feed ad libitum. Both experimental groups had lower triiodothyronine (T3) and thyroxine levels than fed rats; T3 levels were lowest in zinc-deficient animals. The content of thyrotrophin-releasing hormone (TRH) in the hypothalamus of zinc-deficient rats was lower than controls. No difference in labeled iodine uptake by the thyroid was observed between zinc deficiency and starved groups, nor in thyrotropin-stimulating hormone (TSH) response of the pituitary to TRH, although both were significantly lower than in fed rats. These findings suggest that zinc deficiency, more than calorie restriction, lowers T3, perhaps by impairing its extrathyroidal synthesis.
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