Abstract
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 < 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.
Get full access to this article
View all access options for this article.