alpha-Lactalbumin-casein induction in virgin mouse mammary explants: dose-dependent differential action of cortisol

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Science  21 Mar 1980:
Vol. 207, Issue 4437, pp. 1367-1369
DOI: 10.1126/science.6986657


The interplay of insulin, cortisol, and prolactin induces synthesis of casein and alpha-lactalbumin in cultured mammary explants from mature virgin mice. A striking difference has been found between the optimal concentrations of cortisol required for maximal induction of the two milk proteins in vitro: 3 x 10(-8) molar for alpha-lactalbumin and 3 x 10(-6) molar for casein. Moreover, 10(-7) to 10(-5) molar cortisol caused progressive inhibition of alpha-lactalbumin accumulation. Such differential actions of cortisol may partly account for the asynchronous synthesis of the two proteins during pregnancy.