Alcohol intake during pregnancy reduces offspring bone epiphyseal growth plate chondrocyte proliferation through transforming growth factor β-1 inhibition in the Sprague Dawley rat humerus

Intrauterine alcohol exposure delays bone maturation and intensifies osteoporosis and fracture risk. As moststudies emphasize the neurological aspects of intrauterine alcohol exposure, there is a lack of research on the implicationspertaining to osseous tissue. Previous studies investigated these effects in fetuses, with limited studies on postnatal life. Postnatal studies are crucial since peak bone growth occurs during adolescence. This study aimed at assessing the effectsof prenatal alcohol exposure on the humerus proximal and distal growth plate chondrocytes in 3-week-old rats. SpragueDawley rats (n=9) were assigned to either the ethanol group (n=3), saline (n=3), and untreated (n=3) group and time-mated. Once pregnant, as confirmed by the presence of a copulation plug, the former 2 groups were treated with 0.015 ml/g of 25.2%ethanol and 0.9% saline. The untreated group received no treatment. The left humeri belonging to 6 pups per group wereused. Serial sections were cut with a microtome at 5 µm thickness. These sections were stained with haematoxylin and eosinfor assessment of normal morphology or immunolabeled with anti-Ki-67 and transforming growth factor β-1 (TGFβ-1)antibody. Prenatal alcohol exposure adversely effected the growth plate sizes and the number of cells in the proliferative zone. Fewer TGFβ-1 immunopositive and proliferative chondrocytes were found using the anti-Ki-67 antibody. This may explainthe growth retardation in offspring exposed to gestational alcohol, showing that gestational alcohol exposure inhibits cellproliferation, aiding the diminished stature.