Postnatal exposure to a glyphosate-based herbicide interferes with the development and growth of the mammary gland of pre-pubertal Ewe lambs

The aim of the present study was to evaluate whether early postnatal exposure to a glyphosate-based herbicide (GBH) alters pre-pubertal mammary development in Friesian lambs. To this end, from postnatal day 1-14, ewe lambs were exposed subcutaneously or orally to GBH (2 mg/kg bw/day) or vehicle (control) and mammary gland biopsies were obtained at 45 days of age. GBH-exposed lambs exhibited larger mammary ducts and less area occupied by terminal duct lobular units than controls, accompanied by an increase in the area of adipocytes in the mammary stroma. Lambs subcutaneously exposed to GBH showed increased protein expression of estrogen receptor alpha; however, both GBH-exposed groups had decreased mRNA expression of this receptor. Control lambs showed nuclear progesterone receptor (PR) protein expression, whereas GBH-exposed animals showed cytoplasmic PR expression; both GBH-exposed groups exhibited decreased mRNA expression of PR. GBH-exposed lambs also had decreased epithelial cell proliferation. Regarding insulin-like growth factors, both groups showed similar IGF-1 mRNA and protein expression but decreased expression of its receptor, and increased IGFBP5 expression. In addition, phosphorylated AKT was only observed in the mammary gland of control lambs. Our results show that early postnatal exposure to GBH, regardless of the exposure route, affects the IGF-1 system and

Automated summary

The aim of this study was to assess the effects of early postnatal exposure to a glyphosate-based herbicide (GBH) on pre-pubertal mammary development in Friesian lambs. GBH-exposed lambs exhibited larger mammary ducts and decreased area occupied by terminal duct lobular units, accompanied by an increase in adipocyte area in the mammary stroma. The expression of estrogen receptor alpha and progesterone receptor was altered in the GBH-exposed lambs, as well as decreased epithelial cell proliferation and changes in the IGF-1 system.