Gertler, A., The Hebrew University of Jerusalem, Faculty of Agriculture, Department of Agricultural Biochemistry, Rehovot, 76100, Israel
Cohen, N., The Hebrew University of Jerusalem, Faculty of Agriculture, Department of Agricultural Biochemistry, Rehovot, 76100, Israel
Maoz, A., Agricultural Research Organization, Beit-DaganIsrael

Explants from the mammary gland of 6 lactating cows were cultured in M-199 medium containing insulin (1.0 μg/ml) and hydrocortisone (0.5 μg/ml) and supplemented with bPRL (0.2-1.0 μg/ml) or oGH (0.1, 0.5 and 2.5 μg/ml) or bGH or hGH (0.2 and 1.0 μg/ml). It was found that neither oGH nor bGH significantly increased (P < 0.05) the casein and fat synthesis and α-lactalbumin secretion above the control level. A significant and almost equal increase was, however, observed in the presence of bPRL and hGH, but was not influenced by the simultaneous addition of oGH to bPRL-containing medium (both at 0.5 μg/ml). Various hormonal treatments did not affect casein secretion and glucose uptake. High correlations (r = 0.89-0.97) were found between the mean values for casein and fat synthesis and α-lactalbumin secretion. Our results suggest that (a) the in vivo galactopoietic activity of bGH does not result from a direct effect of synthetic capacities on the mammary gland, and (b) hGH is a potent lactogen in the organ culture of bovine lactating mammary tissue. © 1983.