Abstract
During the last decade a great concern has developed for determining what factors
influence bone mineral accretion in healthy children. Mother’s milk represents the
primary source of calcium and other nutrients in the neonate. The development of bone
and adipose tissue has common origins. Since early weaning decreases adipogenesis
in neonate, our aim was to evaluate bone metabolism in 2 models of early weaning (EW)
in neonate rats. Lactating rats were separated into 3 groups: control: pups had free
access to milk; MEW: dams were involved with a bandage mechanically (M) interrupting
lactation in the last 3 days; and PEW: dams were pharmacologically (P) treated to
block prolactin (0.5 mg bromocryptine/twice a day) 3 days before standard weaning.
Significant difference had p<0.05. At weaning, MEW and PEW pups presented lower body
weight ( − 18% and − 15%), total body fat ( − 26% and − 27%), total bone mineral
density ( − 7% and − 6%), total bone mineral content ( − 30% and − 32%), bone area
( − 28% and − 30%), serum osteocalcin ( − 20% and − 55%), and higher C-terminal
cross-linked telopeptide of type I collagen (CTX-I) (1.3 and 1.1-fold increase). However,
serum ionized calcium was lower only in MEW pups ( − 34%), 25-hydroxyvitamin D was
higher (1.4-fold increase), and PTH was lower ( − 26%) only in PEW group. The present
study shows that both early weaning models leads to an impairment of osteogenesis
associated with lower adipogenesis by different mechanisms, involving mainly changes
in vitamin D and PTH.
Key words
lactation - bone - early weaning - calcium - vitamin D - PTH
