scholarly journals Short Communication: Intramammary Infusion of IGF-I Increases Bromodeoxyuridine Labeling in Mammary Epithelial Cells of Prepubertal Heifers

2005 ◽  
Vol 88 (8) ◽  
pp. 2771-2773 ◽  
Author(s):  
L.F.P. Silva ◽  
J.S. Liesman ◽  
B.E. Etchebarne ◽  
M.S. Weber Nielsen ◽  
M.J. VandeHaar
1989 ◽  
Vol 123 (2) ◽  
pp. 319-326 ◽  
Author(s):  
S. J. Winder ◽  
A. Turvey ◽  
I. A. Forsyth

ABSTRACT Ovine mammary epithelial cell clumps (30–90 μm) were plated onto attached gels of rat tail collagen in serum-free medium. Synthesis of DNA by these cultures could be stimulated by insulin-like growth factor-I (IGF-I) with a median effective dose of 5 μg/l, irrespective of stage of pregnancy. The time-course of response, however, was significantly slower in cells prepared from mammary tissue of non-pregnant and early pregnant sheep compared with sheep later in pregnancy. IGF-II had approximately 10% of the potency of IGF-I in stimulating DNA synthesis. Insulin acted over a wide concentration range and produced a maximum rate of stimulation not significantly different from that produced by IGF-I. These results are consistent with actions through the type-I IGF receptor although insulin may also act through its own receptor, possibly stimulating local IGF-I production. It is concluded that IGF-I is an important mitogen for ovine mammary epithelial cells. Journal of Endocrinology (1989) 123, 319–326


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