The relationship between the insulin content and inhibitory effects of bovine colostrum on protein breakdown in cultured cells

Abstract

Protein Degradation in ten mammalian cell lines is markedly inhibited by small amounts of bovine colostrum. This response is consistent with the growth-promoting activity of colostrum that has been reported previously. Fractionation of colostrum on DEAE cellulose showed that most of the inhibitory activity against protein breakdown on H35 cells coeluted with insulin. Insulin concentrations in different batches of bovine colostrum ranged from 0.67 nM to 5.7 nM, approximately 100-fold higher than in blood. The sensitivity of protein breakdown in H35 or MH1C1 hepatoma lines to these colostrum samples was proportional to their insulin concentrations and could largely be accounted for by the amount of insulin present. Removal of insulin from colostrum by means of a protein A-anti-insulin antibody affinity column was accompanied by a loss of the ability of colostrum to inhibit protein breakdown in H35 or MH1C1 cells. However, in IMR90 fibroblasts, a cell line with a similar sensitivity to colostrum as the two hepatomas but very insensitive to insulin, protein breakdown was still inhibited by the insulin-free colostrum. These results suggest that, whereas the effect of bovine colostrum in H35 or MH1C1 cells is actually a response to insulin, different growth factors in colostrum account for the inhibition of protein breakdown in other cell lines.

Whey Protein Concentrate Hydrolysate Prevents Bone Loss in Ovariectomized Rats

“…Whey protein is an industrially obtained by-product of the cheese and casein manufacturing process. Highly active molecules such as epidermal growth factor, 16 colony-stimulating factor, 17 TGFa, b, 18,19 insulin-like growth factor, 20 and fibroblast growth factor 21 have been isolated from whey protein. These protein components can stimulate growth or differentiation of various cell lines in culture, including bone cells.…”

Insulin and glucose in neonatal calves after peroral insulin and intravenous glucose administration

“…There are high amounts of insulin in bovine colostrum (Ballard et al, 1982;Slebodzinski et al, 1986;Malven et al, 1987; Ronge and Blum, 1988; Collier et al, 1989;Wahab et al, 1989;Griitter and Blum, un-published data), which rapidly decrease to the low levels present in milk during later stages of lactation. However, only few investigations have been carried out on insulin in newborn calves (Young et al, 1970;Breier et al, 1988;Ronge and Blum, 1988;Oda et al, 1989).…”

Hormones in bovine milk and milk products: A survey

“…Insulin content in colostrum is between 0.67 and 5.0 nM, which is 100-fold higher than the concentration in the blood plasma (Ballard, Nield, Francis, Dahlenburg, & Wallace, 1982). According to Malven (1977), insulin concentrations in milk varied from 37.1714 ng mL -1 during the pre-partum period, to 6.272.1 ng mL -1 during post-partum and 5.570.6 ng mL -1 after parturition.…”