The purpose of this study was to examine the effects of malnutrition d
uring the first 2 wk of intrauterine life on the regulation of energy
metabolism and the activity of brown adipose tissue in rats at 53 d of
age. Intrauterine malnutrition led to an imbalance in the control of
energy metabolism that was influenced by gender. In males, the intraut
erine malnutrition resulted in impairment of normal weight gain and fa
t deposition during 1 to 53 d of age, in association with low plasma t
otal triiodothyronine concentration, in spite of normal food intake. I
n contrast, the intrauterine malnutrition in females led to a marked f
at accumulation by 53 d of age with normal food intake, and decreased
brown adipose tissue weight, protein content and cytochrome c oxidase
activity, indicating a lower sympathetic activity. These data indicate
that nutrient availability during the first 2 wk of intrauterine life
determines the control of energy utilization during early post-weanin
g period.