title: Suppression of ovarian secretions before puberty strongly affects mammogenesis in the goat.
abstract: The objective of this study was to provide insight into the biological mechanisms underlying mammary development and the role of the ovaries in prepubertal caprine mammogenesis using a serial ovariectomy approach. Young Alpine goats were ovariectomized (Ovx) or sham-operated (Int) at three periods before puberty (G1=1 month, G2=2 month and G3=3 months of age) and one after puberty (G7=7 months of age). The goats were slaughtered at 9 months of age and mammary glands were removed. Ovariectomy performed at 1, 2 and 3 months of age caused a 50% reduction in DNA concentration, in mammary tissue taken from the parenchyma-stroma border region. Morphological analysis of mammary tissue sections indicated that the parenchymal structures of Ovx goats were negatively affected by ovariectomy. Goats ovariectomized before 2 months of age (Ovx-1 and Ovx-2) showed a significant decrease in the percent of cells proliferating in mammary glands of 9-month old goats (proliferating cell nuclear antigen expression and antigen Ki67-positive cell number). Also, goats ovariectomized at 1 and 2 months of age had reduced matrix metalloprotease 2 activity at 9 months of age. E-cadherin was strongly decreased in goats ovariectomized before 2 months of age (80 and 85% in Ovx-1 and Ovx-2 goats, respectively). Quantitative PCR analysis of transcripts encoding for oestrogen (ERα) and progesterone receptors (PR) and immunodetection of ERα showed that ovariectomy at 1 and 2 months of age strongly inhibited the transcription of ERα and PR in the mammary gland. We conclude that ovariectomy before 3 months of age markedly impaired parenchymal development. These findings suggest that prepubertal mammogenesis in goats depends on the ovaries to initiate mammary epithelial cell proliferation and mammary gland remodelling.
authors.affiliation: INRA UMR 1080 Dairy Production, F-35000 Rennes, France.
authors.forename: Lucile
authors.initials: L
authors.lastname: Yart
authors.forename: Laurence
authors.initials: L
authors.lastname: Finot
authors.forename: Pierre-Guy
authors.initials: PG
authors.lastname: Marnet
authors.forename: Frédéric
authors.initials: F
authors.lastname: Dessauge
mesh_terms: D000375:Aging; D000818:Animals; D015820:Cadherins / Q000032:analysis; D049109:Cell Proliferation; D004247:DNA / Q000032:analysis; D047628:Estrogen Receptor alpha / Q000032:analysis / Q000235:genetics; D005260:Female; D006041:Goats / Q000254:growth & development* / Q000502:physiology; D008321:Mammary Glands, Animal / Q000737:chemistry / Q000166:cytology / Q000254:growth & development*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D010052:Ovariectomy / Q000662:veterinary; D010053:Ovary / Q000502:physiology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012333:RNA, Messenger / Q000032:analysis; D011980:Receptors, Progesterone / Q000235:genetics; D012741:Sexual Maturation / Q000502:physiology*
chemical_list: D015820:Cadherins; D047628:Estrogen Receptor alpha; D012333:RNA, Messenger; D011980:Receptors, Progesterone; D004247:DNA; D020778:Matrix Metalloproteinase 2