Response of Pituitary-Thyroid Axis to a Short-Term Shift in Deuterium Content in the Body.

We studied functional changes in rat pituitary-thyroid axis after a short-term shift in deuterium body content. Male Wistar rats consumed deuterium-enriched (500,000 ppm) or deuterium-depleted water (10 ppm) for 24 h. Rats of both experimental groups demonstrated elevated concentration of bound with transport proteins thyroxine and reduced level of thyroid-stimulating hormone in serum. No changes in the rate of thyroxine conversion to triiodothyronine were found. Thus, both the increase and reduction of deuterium body content produced similar changes in the function of the pituitary-thyroid axis with primary affection of the thyroid gland, indicative of its higher sensitivity to shift in deuterium levels.