Exposure to a Glyphosate-based Herbicide Alters the Expression of Key Regulators of Mammary Gland Development on Pre-pubertal Male Rats. (June 2020)

• Record Type: Journal Article
• Authors: Gomez, Ayelen L.; Altamirano, Gabriela A.; Tschopp, María V.; Bosquiazzo, Verónica L.; Muñoz-de-Toro, Mónica; Kass, Laura
• Is Part Of: Toxicology. Volume 439(2020)
• Publication Date: 2020-06
• Subjects: Glyphosate-based herbicide -- male -- rat mammary gland -- ductal morphogenesis -- growth factors; α-SMA α smooth muscle actin -- AR androgen receptor -- Areg amphiregulin -- Ccnd1 cyclin D1 -- DAB diaminobenzidine -- EDCs endocrine disrupting chemicals -- EGFR epidermal growth factor receptor -- ERK extracellular-regulated kinase -- ESR1 estrogen receptor alpha -- E2 estradiol -- F0 dams directly exposed to GBH -- GBH glyphosate-based herbicide -- GD gestational day -- IF immunofluorescence -- IGF1 insulin-like growth factor 1 -- IGF1R insulin-like growth factor 1 receptor -- IOD integrated optical density -- LD lactation day -- MAPK mitogen-activated protein kinase -- PND postnatal day -- TEBs terminal end buds -- T testosterone; Toxicology -- Periodicals; Chemicals -- Physiological effect -- Periodicals; 615.9005
• DOI: 10.1016/j.tox.2020.152477
• Languages: English
• ISSNs: 0300-483X

Abstract

Abstract: We previously reported that exposure during gestation and lactation to a low dose of glyphosate-based herbicide (GBH) reduced the area and perimeter of male offspring mammary gland at postnatal day 60 (PND60), whereas a higher dose increased the longitudinal growth of the gland. Here, our aim was to assess whether perinatal exposure to GBH exhibits endocrine disruptive action in male mammary gland at an early time point (pre-puberty), which could be related to the changes observed after puberty. We also wanted to explore whether an early evaluation of the male rat mammary gland is appropriate to assess exposure to potential endocrine disrupting chemicals (EDCs). Pregnant rats were orally exposed, through the diet, to vehicle (saline solution), 3.5 or 350 mg/kg/day of GBH from gestational day 9 until weaning. At PND21, the male offspring were euthanized, and mammary gland samples were collected. The histology and proliferation index of the mammary glands were evaluated, and the mRNA expression of estrogen (ESR1) and androgen (AR) receptors, cyclin D1 (Ccnd1), amphiregulin (Areg), insulin-like growth factor 1 (IGF1), epidermal growth factor receptor (EGFR) and IGF1 receptor (IGF1R) were assessed. Moreover, the phosphorylated-Erk1/2 (p-ERK1/2) protein expression was determined. No differences were observed in mammary epithelial structures and AR expression between experimental groups; however, the proliferation index was reduced in GBH3.5-exposed males. This result was associated with decreased ESR1, Ccnd1, Areg, IGF1, EGFR and IGF1R mRNA expressions, as well as reduced p-Erk1/2 protein expression in these animals. ESR1, Ccnd1, IGF1R and EGFR expressions were also reduced in GBH350-exposed males. In conclusion, the mammary gland development of pre-pubertal male rats is affected by perinatal exposure to GBH. Although further studies are still needed to understand the molecular mechanisms involved in GBH350 exposure, the present results may explain the alterations observed in mammary gland growth of post-pubertal males exposed to low doses of GBH. Our results also suggest that early evaluation of the male rat mammary gland is useful in assessing exposure to potential EDCs. However, analysis of EDCs effects at later time points should not be excluded.