Submitted to: Journal of Mammary Gland Biology and Neoplasia
Publication Type: Review Article
Publication Acceptance Date: 12/2/1999
Publication Date: N/A
Citation: Akers, R.M., Mcfadden, T.B., Purp, M., Vestergaard, K., Sejrsen, K., Capuco, A.V. 2000. Local igf-i axis in peripubertal ruminant mammary development.Journal of Mammary Gland Biology and Neoplasia. 5(1):43-51. Interpretive Summary:
Technical Abstract: The regulation of mammary growth and development in heifers is accomplished by complex interactions of hormones, growth factors, and extracellular matrix molecules. Many of these growth stimulators are believed to be locally produced in the mammary gland and to be affected by developmental and nutritional status. Although dogma suggests estrogen and growth hormone are of primary importance in pubertal mammogenesis, data summarized in this review suggest that IGF-I and IGF binding proteins are especially important locally produced growth regulators in peripubertal ruminants. Animal data to support this assertion come from studies of ovariectomized heifers in which increased stromal IGFBP-3 and reduced IGF-I corresponds with a failure of udder development. Similarly, reduced mammary development with over feeding coincides with reduced mitogenic activity of mammary tissue extracts and altered concentrations IGF-I and IGFBPs. In vitro studies convincingly demonstrate that much of the mitogenic activity of mammary extracts or serum can be attributed to IGF-I and that alterations in IGFBP-3 modulate it's effectiveness. In short, somewhat analogous to second messenger mechanism of action for protein hormones, it is likely that local mammary derived growth factors ultimately explain many of the effects attributed to the classic mammogenic hormones.