Chronic Effects of Maternal Malnutrition during Lactation: Severe Influences on Cortical Bone Mass of Wistar Rats Femur

Introduction: Malnutrition is a world health problem and has high incidences in developing countries. It is known that the nutritional status of the mother during gestation and lactation affects the growth and development of its child. Maternal malnutrition during breastfeeding has been shown to cause alterations of thyroid function and bone tissue. Aim: The present study aimed to evaluate the chronic effects in bone tissue of energy-protein restriction in rats during lactation period through a histological and morphometric analysis of the cortical mass of the femur. Materials and Methods: At parturition, Wistar rat dams were divided in three groups: (1) Control group - which received 23% protein diet without restrictions; (2) Protein-Energy restriction group - which received 8% protein diet; (3) Energy restriction group - which received 23% protein diet in limited amounts, according to the ingestion of the second group. Each group had 12 pups. After weaning, all pups were separated from its dams and received free access to 23% protein diet until 180 days and then euthanized. Afterwards, the femur of these specimens were excised and fixed in 4% formaldehyde solution and decalcified by EDTA. 10 µm thick transverse sections on the middle third of the femur diaphysis were performed. Then, the tissue was stained with Haematoxylin/Eosin and analysed under a microscope. Results: The cortical area of the control, energy restriction and protein-energy restriction groups were, respectively: 6.54±0.23 µm, 5.51±0.29 µm and 6.18±0.19 µm, while the medullary cavity showed the following results: 3.65±0.16 µm, 4.1±0.20 µm and 3.53±0.12 µm. Reduction of the cortical area and an increase of medullary zone were observed on the protein-energy restriction group. Conclusion: Maternal malnutrition during lactation has negative effects on femur growth even after normalization of the diet in adult aged Wistar rats.