title: Prolactin's effects on lipoprotein lipase (LPL) activity and on LPL mRNA levels in cultured mouse mammary gland explants.
abstract: The in vitro effects of prolactin (PRL) on lipoprotein lipase (LPL) activity and on LPL mRNA levels were studied in cultured mammary tissues derived from mid-pregnant mice. Mouse mammary gland tissues were initially incubated for 24 hr in M199 media containing 1 microg/ml insulin and 10(-7) M cortisol. A subsequent treatment of the tissues with 1 microg/ml PRL caused a 76% increase in heparin-releasable LPL (hrLPL) activity after 24 hr. A significant increase in LPL activity was detected 16 hr after PRL addition, but not at earlier times. PRL at 100 ng/ml elicited a maximum stimulation of LPL activity. When Northern hybridization techniques were employed, PRL was also found to increase the tissue content of LPL mRNA; this effect was initially detected after a 6-hr PRL treatment employing PRL concentrations of 50 ng/ml and above. Specificity studies revealed that only lactogenic hormones stimulated LPL activity and LPL mRNA accumulation in cultured mammary tissues. PRL also expressed a small (25% increase), but significant, effect on ATP citrate-lyase activity in mammary tissues cultured for more than 6 hr with the hormone.
authors.affiliation: Department of Physiology, Wayne State University, Detroit, Michigan 48201, USA.
authors.forename: J
authors.initials: J
authors.lastname: Hang
authors.forename: J A
authors.initials: JA
authors.lastname: Rillema
mesh_terms: D001275:ATP Citrate (pro-S)-Lyase / Q000378:metabolism; D000818:Animals; D015152:Blotting, Northern; D004305:Dose-Response Relationship, Drug; D005260:Female; D008071:Lipoprotein Lipase / Q000235:genetics / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D009924:Organ Culture Techniques; D011247:Pregnancy; D011388:Prolactin / Q000494:pharmacology*; D012313:RNA / Q000302:isolation & purification; D012333:RNA, Messenger / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D012313:RNA; D011388:Prolactin; D001275:ATP Citrate (pro-S)-Lyase; D008071:Lipoprotein Lipase