Hormonal regulation of protein kinase C in the mouse mammary gland.
The hormonal regulation of protein kinase C (PKC) induction over 3 to 14 days was investigated in the mouse mammary gland in vitro and in vivo. In intact mice, estradiol (1 microgram/mouse injected daily for 2 weeks) stimulated PKC activity 70%, while progesterone (1 mg/mouse injected daily) inhibited it by 30%. Prolactin, whose levels were elevated for 2 weeks by two pituitary isografts, had no effect. When mammary gland explants were cultured in insulin and cortisol, the further addition of estradiol (1 ng/ml), progesterone (1 microgram/ml), or prolactin (1 microgram/ml) did not alter PKC activity after 3 days. These data suggest the following conclusions: although previous studies have implicated prolactin in the transient, calcium-phospholipid activation of PKC, it does not appear to elevate total levels of this kinase over prolonged periods. In contrast, the sex steroids do appear to affect long-term levels of this kinase; furthermore, this latter effect may be indirect.
D000818:Animals; D004790:Enzyme Induction; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D012739:Gonadal Steroid Hormones / Q000494:pharmacology*; D006854:Hydrocortisone / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D008321:Mammary Glands, Animal / Q000201:enzymology*; D051379:Mice; D011374:Progesterone / Q000494:pharmacology; D011388:Prolactin / Q000494:pharmacology; D011493:Protein Kinase C / Q000096:biosynthesis*
D012739:Gonadal Steroid Hormones; D007328:Insulin; D011374:Progesterone; D004958:Estradiol; D011388:Prolactin; D011493:Protein Kinase C; D006854:Hydrocortisone