Chronic alcohol ingestion decreases pituitary-thyroid axis measures in Fischer-344 rats

In a chronic feeding study adult male Fischer-344 rats (n = 12) were fed a nutritionally complete liquid diet containing 10% (w/v) ethanol for 40 days while control animals (n = 12) were pair fed a nutritionally complete isocaloric diet in which dextrose was substituted for ethanol. Treated animals were gradually introduced to and withdrawn from the 10% diet. At the end of the study and at sacrifice ethanol-fed rats had gained slightly more weight than pair-fed controls. They also showed a significant decrease in total thyroxine, free thyroxine, L-triiodothyronine, reverse L-triiodothyronine, and basal thyroid-stimulating hormone. These differences did not appear to result from caloric deprivation alone. Possible explanations for some of these thyroidal changes are discussed.