Protein-energy malnutrition in rats during pregnancy modifies the effects of caffeine on fetal bones

The mandibles and long bones of newborn rats were analyzed for the effects of maternal caffeine consumption and protein-energy malnutrition. On d 13 of gestation, dams were randomly picked and divided into four groups. Group 1 received a 20% protein diet ad libitum. Group 2 was pair-fed with group 1 a 20% protein diet with a caffeine supplement (2 mg/100 g body wt). Group 3 received a 6% protein diet ad libitum. Group 4 was pair-fed with group 3 a 6% protein diet with caffeine. Within 8 h of delivery, all pups were weighted. Randomly selected pups were injected with 14C proline to study collagen synthesis of bones. Other pups were injected with 45Ca to study mineralization of bones. Although the average litter size from the 20% protein groups with or without caffeine did not show much variation, fetal resorption and stillbirths were higher in litters from group 4 compared to those from group 3. The mandibular weights of pups from group 2 was less than those from group 1, whereas weight of long bones of those from group 4 was heavier. The rate of collagen synthesis and calcium content of the mandible of group 4 and 45Ca uptake of the mandible of groups 2 and 4 were greater than that of the corresponding noncaffeine group. The rate of collagen synthesis, hydroxyproline content, 45Ca uptake and calcium content of the long bones of groups 2 and 4 were greater than that of the noncaffeine groups. The findings suggest that nutritional factors and the effects of caffeine are closely interrelated in the growth and development of the fetus and bone in newborn rats.