Effects of hormones on protein and amino acid metabolism in mammary-gland explants of mice.
The effects of insulin, cortisol and prolactin on amino acid uptake and protein biosynthesis were determined in mammary-gland explants from mid-pregnant mice. Insulin stimulated [3H]leucine incorporation into protein within 15 min of adding insulin to the incubation medium. Insulin also had a rapid stimulatory effect on the rate of aminoiso[14C]butyric acid uptake, but it had no effect on the intracellular accumulation of [3H]leucine. Cortisol inhibited the rate of [3H]leucine incorporation into protein during the initial 4h of incubation, but it had no effect at subsequent times. [3H]Leucine uptake was unaffected by cortisol, but amino[14C]isobutyric acid uptake was inhibited after a 4h exposure period to this hormone. Prolactin stimulated the rate of [3H]leucine incorporation into protein when tissues were exposed to this hormone for 4h or more; up to 4h, however, no effect of prolactin was detected. At all times tested, prolactin had no effect on the uptake of either amino[14C]isobutyric acid or [3H]leucine. Incubation with actinomycin D abolished the prolactin stimulation of protein biosynthesis, but this antibiotic did not affect the insulin response. A distinct difference in the mechanism of action of these hormones on protein biosynthesis in the mammary gland is thus apparent.
D000621:Aminoisobutyric Acids / Q000378:metabolism; D000818:Animals; D003609:Dactinomycin / Q000494:pharmacology; D005260:Female; D006854:Hydrocortisone / Q000494:pharmacology*; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D007930:Leucine / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000378:metabolism*; D051379:Mice; D011247:Pregnancy; D011270:Pregnancy, Animal; D011388:Prolactin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014176:Protein Biosynthesis; D013997:Time Factors
D000621:Aminoisobutyric Acids; D007328:Insulin; D003609:Dactinomycin; D011388:Prolactin; D007930:Leucine; D006854:Hydrocortisone