Changes in insulin-like growth factor-binding proteins in bovine mammary secretions associated with pregnancy and parturition

Abstract

The bovine mammary gland accumulates large quantities of insulin-like growth factors (IGFs) and IGF-binding proteins (IGFBPs) during late gestation which are secreted at parturition. The present study was conducted to determine the changes in the profiles of IGFBPs secreted by the mammary gland and in blood during late gestation and early lactation in dairy cows. Ligand blotting of serum and mammary secretions showed that IGFBPs of Mr 25,000, 30,000, 34,000, 42,000, 46,000 and greater than 200,000 were present in both fluids. The binding activity of the 42-46,000 Mr IGFBP predominated in prepartum mammary secretions and colostrum but was reduced postpartum. The binding activities of the 30,000 and 34,000 Mr IGFBPs, relative to other IGFBPs, were increased postpartum. Concentrations of IGF-I and IGF-II in mammary secretions declined from 347.1 and 181.1 nmol/litre 1 week prepartum to 0.7 and 0.3 nmol/litre 1.5 weeks postpartum. The volume of mammary secretions obtained was 0.109 litre and 6.690 litres at 1 week prepartum and 1.5 weeks postpartum respectively. In prepartum serum, the greatest binding activity was at Mr 42-46,000. The activity at this Mr decreased at parturition but was restored postpartum. The binding activities of the 30,000 and 34,000 Mr IGFBPs were increased around parturition. The 25,000 Mr IGFBP had minor activity during all periods. IGF-I concentrations decreased from 10.6 nmol/litres 1 week prepartum to 4.7 nmol/litres 1.5 weeks postpartum but IGF-II concentrations remained constant. In conclusion, IGFBP activity secreted by the mammary gland shifts from primarily Mr 42-46,000 prepartum to Mr 30,000 postpartum.(ABSTRACT TRUNCATED AT 250 WORDS)

Periparturient Endocrine and Metabolic Changes in Healthy Cows and in Cows Affected by Mastitis

“…Our results confirm that the act of parturition in cows is accompanied by marked changes in circulating hormone profiles. The general trends, such as the peak in plasma cortisol and the trough in insulin concentrations at the onset of parturition, confirmed earlier observations (Schams et al, 1991; Skaar et al, 1991; Hydbring et al, 1999). The overall profile indicates marked energy deficiency from the day of calving (McGuire et al, 1995).…”

“…In the other six cases, the relative amounts and time‐related changes in the characteristic IGFBP‐3 doublet were variable. Faint IGFBP‐3 bands on the day of calving occurred in four cases including both healthy cows (nos 323 and 3122), the cow with later S. aureus infection (no 5896) and cow 6204 (Figs 2 and 3), which is similar to the pattern observed by Skaar et al (1991). Western ligand blots for IGFBP‐3 do not provide a reliable estimation of the amount of ternary complexes with IGF and acid‐labile subunit (ALS) in the circulation, because the complexes can remain intact after partial IGFBP‐3 proteolysis (Baxter, 2000).…”

Growth factors from bovine milk and colostrum: composition, extraction and biological activities

“…Thereafter, many growth factors were identified in colostrum and milk and partly associated with the growth-promoting or growthinhibitory activity (depending on cell type) of colostrum and milk. At the present time, the growth factors that have been identified in bovine colostrum and milk are the following: EGF [89,105,173,238], BTC [7,50], IGF-I and/or IGF-II [14,16,30,38,51,59,64,73,99,125,126,140,143,147,164,180,189,190,192,204,206,229,232], TGF-β1 and/or TGF-β2 [14,44,51,64,94,151,179,211,212,218,225,227], FGF1 and/or FGF2 [83,104,178,189], and PDGF [14,199,200]. However, only a few studies have re...…”

“…This information has been added in Table I whenever available. It is known that the growth factor concentration in colostrum is the highest during the first hours of calving and generally declines substantially in a time-dependent manner following peak concentration [7,16,30,38,64,89,105,108,109,125,143,147,151,180,190,192,198,204,206,210,229,232,240]. In addition, the total protein concentration decreases markedly during the first four days of lactation [7,64,93,151,173].…”

Insulin-Like Growth Factor-Binding Proteins in Serum and Other Biological Fluids: Regulation and Functions*

“…In addition, IGFBP-4 has been identified in rat, porcine, and bovine milk (85,86). In addition, IGFBP-4 has been identified in rat, porcine, and bovine milk (85,86).…”