Feed efficiency and norepinephrine turnover in iron deficiency.
Norepinephrine turnover and energetic efficiency studies were conducted in three groups of male Sprague-Dawley rats placed on low iron diets for 5 weeks on weaning. Iron-deficient rats had significant anemia (hematocrit less than 20%) and growth retardation relative to pair-fed and ad libitum fed controls who received the same diet plus weekly iron dextran injections. Energetic efficiency over a 7-day period was nearly 30% less in anemic animals. This was associated with significantly higher rates of norepinephrine turnover in brown adipose tissue (110%) and heart (330%) with significant hypertrophy in both tissues. There was no difference in body composition in ad libitum groups. Plasma triiodothyronine and thyroxine were reduced by 37% in iron deficients compared to controls. Thus 39% increase in caloric requirements in iron deficiency is associated with increased sympathetic and perhaps thermogenic activity in brown adipocytes.
D000273:Adipose Tissue / Q000378:metabolism; D000747:Anemia, Hypochromic / Q000378:metabolism*; D000818:Animals; D004734:Energy Metabolism; D006400:Hematocrit; D008297:Male; D009206:Myocardium / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013963:Thyroid Hormones / Q000097:blood
D013963:Thyroid Hormones; D009638:Norepinephrine