The reversal of cortisol-induced inhibition of alpha-lactalbumin production by prostaglandins in the mouse mammary gland in culture.

Abstract

Previous studies of cultured mammary gland from mid-pregnant mice showed that addition of cortisol at concentrations ranging from 3 X 10(-8) to 3 X 10(-6) M caused progressive increases in casein accumulation but marked decreases in alpha-lactalbumin accumulation in tissue cultured in the presence of insulin and prolactin (Ono, M., and Oka, T. (1980) Cell 19, 473-480). The present studies showed that the addition of prostaglandin (PG) E2 blocked the inhibitory effect of cortisol on the synthesis and accumulation of alpha-lactalbumin without affecting casein production. The effect of PGE2 was observed at a concentration as low as 6.6 X 10(-8) M and was maximal at 2.8 X 10(-6) M. Among various prostaglandins tested, PGE2 and PGE1 were most potent and other prostaglandins were also active with the potency decreasing in the following order: PGF1 alpha greater than or equal to PGF2 alpha greater than or equal to PGA2 greater than or equal to PGB2 greater than PGA1 greater than or equal to PGB1. Arachidonic acid was also effective, but only at very high concentrations, 6.6 X 10(-5)-1.6 X 10(-4) M. The ability of prostaglandins to allow a maximal formation of the two milk proteins suggests a possible modulatory role of prostaglandins in hormonal control of milk-protein synthesis.