Milk composition and Bisphenol A exposure

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

Buenos Aires

Congreso; SETAC Latin America 11th Biennial Meeting; 2015

Society of Environmental Toxicology and Chemistry Latin America

In most mammals, milk is the only food source for newbornsand consequently must contain all the key nutrients for normal growth anddevelopment. In essence, milk is composed of milk proteins, milk fat globules,lactose, calcium and water. Its normal composition depends on the correctbiochemical and structural differentiation of the alveolar cells. Environmentalfactors and the diet of the mother also affect milk composition. Therefore, anyinterference with the growth and differentiation of the mammary gland couldimpair the lactational performance of the dams. Our studies evaluate whether Bisphenol A (BPA) modifies mammary glanddifferentiation 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 ratsfrom gestational day 9 (GD9) until weaning. After puberty, F1 females were bredand mammary gland samples were obtained at the end of pregnancy and during early-midlactation. 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, therewas a decrease in alpha-lactalbumin and beta-casein levels that were accompanied by reduced prolactin receptor and Stat5a/b expression. On GD21 and LD2, BPA exposure delayed mammary alveolar maturationand modified the synthesis of milk fat globules. Moreover, beta-casein levels remained decreased not only in mammary gland, but also in milk samples and, BPA-exposed groups had analtered 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 milk. BPA50 F1dams produced milk with higher saturated FA concentration than BPA0.5 and control F1 animals. The increase in milk fat contentand the differences in the milk FA profile exhibited by BPA50 F1 dams wereassociated 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.