Dietary zinc deficiency and supplementation in early life and mammary tumors development in adulthood female rats. Rattus norvegicus

Zinc deficiency during pregnancy and postnatal life can adversely affect the health and predispose to an increased risk of developing human diseases at adulthood. The present study was designed to evaluate whether dietary zinc deficiency or supplementation during the pregnancy, lactation and juvenile stages interferes with the development of mammary tumors induced by 7,12-dimethylbenzanthracene (DMBA) in female Sprague-Dawley (SD) rats. Pregnant females SD were allocated into three groups: dams received diets containing adequate (35 mg/Kg chow), deficient (3 mg/Kg chow) or supplemented (180 mg/Kg chow) zinc levels during gestational day 10 (GD 10) until the litters weaning. Female offspring were allocated into three groups and received the same diets as their dams until postnatal day (PND) 51. At PND 51, females SD (n=16 each group) received a single dose of DMBA (50 mg/kg, ig) for initiation of mammary carcinogenesis, adequate zinc diets and were euthanized at PND 180. Tumors samples were collected and processed for histological evaluation and microarray analysis. Dietary zinc deficiency induced a significant reduction in female offspring body weight evolution at parturition, weaning and pubertal phases. At late in life, the early in life dietary zinc deficiency or supplementation did not alter the latency, incidence, multiplicity and volume or histological types of mammary tumors in relation to the adequate zinc group, and changed the expression of a small amount of genes. The present findings indicate that early-in life dietary zinc deficiency or supplementation did not significantly modify the susceptibility to development of mammary tumors induced by DMBA. Overall design: Pregnant Sprague-Dawley (SD) rats (16 dams /group) were distributed into three groups: ZnA, dams fed adequate zinc diet (35 mg/Kg chow); ZnD, dams fed zinc deficient diet (3 mg/Kg chow); and ZnS, dams fed zinc supplemented diet (180 mg/Kg chow). These experimental diets were provided ad libitum to the dams from GD 10 until lactational day (LD) 21 (weaning). At PND 21, female offspring were allocated in their respective dietary intervention and received the same diet that dams intake during gestation and lactation phases until PND 51 (puberty). At PND 51, all animals received a single intragastric administration (i.g.) of DMBA (50 mg/kg, diluted in canole oil) and were fed adequate zinc diet until PND 180. At PND 180 the animals were euthanized for mammary tumor and gene expression analyses.