Greatly Increased Cancellous Bone Formation With Rapid Improvements in Bone Structure in the Rat Maternal Skeleton After Lactation
Open Access
- 1 November 2002
- journal article
- Published by Oxford University Press (OUP) in Journal of Bone and Mineral Research
- Vol. 17 (11), 1954-1960
- https://doi.org/10.1359/jbmr.2002.17.11.1954
Abstract
There is a decrease in cancellous bone mass and strength during lactation but these are partially or completely reconstituted in the postlactational period. The purpose of this study was to determine changes in cancellous bone structure and formation after lactation in established breeder rats. For this, rats were taken at the end of the second pregnancy (Preg-2) and second lactation (Lac-2) and 2, 4, and 6 weeks after weaning. Nulliparous (NP) groups were included for comparisons. Bone structure was measured using morphometric methods and bone dynamics by histomorphometry. Tibial metaphyseal cancellous bone was lost during the first reproductive cycle, as expected, and again depleted during the Lac-2. Bone formation indices were elevated at the end of Lac-2, compared with those at the end of the second pregnancy or in the nulliparous animals. Within 2 weeks after the second weaning, the amount of double-labeled surface (dLS) increased approximately 800%, the mineralizing surface (MS) increased >400% with similar increases in bone formation rates (BFRs), compared with already elevated bone formation measured at the end of Lac-2. From 2 to 4 weeks after lactation, there were commensurate increases in cancellous bone mass and structural indices with essentially complete restoration of cancellous bone volume and structure compared with that measured at the end of Preg-2. The results show rapid and substantial increases in bone formation with reconstitution of cancellous bone mass and structure after lactation in rats. The skeletal changes that occur during the postlactational period may serve to prepare and protect the maternal skeleton for subsequent reproductive cycles.Keywords
This publication has 34 references indexed in Scilit:
- Skeletal mass, chemistry, and growth during and after multiple reproductive cycles in the ratBone, 1999
- Changes in Bone Mineral Density of Lumbar Vertebrae after Parturition in African Green Monkeys (Cercopithecus aethiops).Experimental Animals, 1996
- Effects of progesterone on postovariectomy bone loss in aged ratsJournal of Bone and Mineral Research, 1990
- A scanning electron microscopic and photon absorptiometric study of the development, prolongation, and pattern of recovery from lactation-induced osteopenia in RatsJournal of Bone and Mineral Research, 1990
- Increased cancellous bone remodeling during lactation in beaglesBone, 1989
- Bone histomorphometry: Standardization of nomenclature, symbols, and units: Report of the asbmr histomorphometry nomenclature committeeJournal of Bone and Mineral Research, 1987
- A new method for the two‐dimensional analysis of bone structure in human iliac crest biopsiesJournal of Microscopy, 1986
- Changes in Body Weight, Kidney Weight and Proximal Tubule Length during Pregnancy in the RatKidney and Blood Pressure Research, 1978
- Calcium deficiency, pregnancy, and lactation in ratsCalcified Tissue International, 1977
- Skeletal Changes during Pregnancy and Lactation in the Rat: Effect of Different Levels of Dietary CalciumBritish Journal of Nutrition, 1952