title: Programmed cell death during mammary tissue involution induced by weaning, litter removal, and milk stasis.
abstract: Programmed cell death in mammary tissue was studied during natural weaning in lactating mice and after litter removal or milk stasis. All treatments stimulated mammary apoptosis, indicating that this process is an integral part of the tissue's involution after lactation. Induction of apoptosis was slower in natural weaning than after litter removal but occurred earlier when mice were concurrently pregnant during natural weaning. Ipsilateral induction of apoptosis by milk stasis in teat-sealed glands indicates that cell death is under local (i.e., intramammary) as well as endocrine regulation. Apoptosis detected by DNA laddering was associated with changes in expression of p53 and bax, two genes implicated in the regulation of cell death, and was accompanied by structural degeneration characteristic of mammary involution. Reciprocal changes in stromelysin mRNA, and that of its inhibitor TIMP-2, suggested that this structural reorganisation was the result of coordinated changes in gene expression favouring proteolysis of the extracellular matrix.
authors.affiliation: Hannah Research Institute, United Kingdom.
authors.forename: L H
authors.initials: LH
authors.lastname: Quarrie
authors.forename: C V
authors.initials: CV
authors.lastname: Addey
authors.forename: C J
authors.initials: CJ
authors.lastname: Wilde
mesh_terms: D000818:Animals; D017209:Apoptosis; D004247:DNA / Q000378:metabolism; D007774:Lactation / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000166:cytology*; D019278:Matrix Metalloproteinase 3; D008666:Metalloendopeptidases / Q000235:genetics; D051379:Mice; D011506:Proteins / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2; D019716:Tissue Inhibitor of Metalloproteinase-2; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D014886:Weaning; D051028:bcl-2-Associated X Protein
chemical_list: C494827:Bax protein, mouse; D011506:Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D019716:Tissue Inhibitor of Metalloproteinase-2; D004247:DNA; D008666:Metalloendopeptidases; D019278:Matrix Metalloproteinase 3