Milk composition and Bisphenol A exposure

GA ALTAMIRANO; M MUÑOZ-DE-TORO; EH LUQUE,; L KASS

Congreso; SETAC LatinAmerica 11thBiennal Meeting; 2015

In most mammals, milk is the only food source for newborns and consequently must contain all the key nutrients for normal growth and development. In essence, milk is composed of milk proteins, milk fat globules, lactose, calcium and water. Its normal composition depends on the correct biochemical and structural differentiation of the alveolar cells. Environmental factors and the diet of the mother also affect milk composition. Therefore, any interference with the growth and differentiation of the mammary gland could impair the lactational performance of the dams. Our studies evaluate whether Bisphenol A (BPA) modifies mammary gland differentiation and milk composition on perinatally exposed animals. BPA (0, 0.5 or 50 μg/kg bw/day) was administered in the drinking water of F0 rats from gestational day 9 (GD9) until weaning. After puberty, F1 females were bred and mammary gland samples were obtained at the end of pregnancy and during early-mid lactation. In addition, milk yield and milk protein and lipid/fatty acid (FA) composition were assessed. Serum levels of glucose, cholesterol and triglycerides were measured as well. On GD18, there was a decrease in α-lactalbumin and β-casein levels that were accompanied by reduced prolactin receptor and Stat5a/b expression. On GD21 and lactation day 2 (LD2), BPA exposure delayed mammary alveolar maturation and modified the synthesis of milk fat globules. Moreover, β-casein levels remained decreased not only in mammary gland, but also in milk samples and, BPA-exposed groups had an altered milk yield pattern during lactation. On LD10, mammary gland histo-architecture was restored and glucose, cholesterol and triglyceride serum levels were similar among groups. However, the milk of BPA-exposed F1 dams had a FA profile and lipid concentration different from those of the control one. BPA50 F1 dams produced milk with higher saturated FA concentration than BPA0.5 and control F1 animals. The increase in milk fat content and the differences in the milk FA profile exhibited by BPA50 F1 dams were associated with a higher body weight gain of the BPA50 F2 pups during lactation. Perinatal exposure to BPA has not only modified milk protein composition, but also FA synthesis and milk FA profile, impairing milk quality and compromising the normal growth of the offspring.