Energy restriction in pregnant and lactating rats lowers bone mass of their progeny

Bone growth and metabolism are studied in 2 groups of 14-day-old rats, a control group and an energy-restricted group whose mothers are submitted to energy restriction (24-hour fasted versus 24-hour standard diet intake) from the 14th day of pregnancy until day 14 after delivery. We obtained a decrease in body weight (−46%) and in plasma FT4 (−47%) and FT3 (−15%) levels. Energy restriction in rats altered bone mineral composition in their pups, especially calcium and phosphorus levels of bone, which decreased by 33% and 19%, respectively. Calcium levels increased by 15% in plasma and decreased by 64% in urine. In contrast, phosphorus levels decreased by 23% in plasma and increased by 61% in urine. These results suggested that fasting accelerated bone resorption activity, where plasma acid phosphatase (ACP) and plasma alkaline phosphatase are increased by 41% and 21%, respectively. We found a negative correlation between FT3 and ACP (r = −0.750, P < .003) and between FT4 and ACP (r = −.905, P < .001). In conclusion, energy restriction in rats during late pregnancy and early postnatal periods seems to engender disorders in bone growth and metabolism of their offspring.