Hang J, Rillema J A
Department of Physiology, Wayne State University, Detroit, Michigan 48201, USA.
Proc Soc Exp Biol Med. 1997 Feb;214(2):161-6. doi: 10.3181/00379727-214-44083.
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.
在来源于妊娠中期小鼠的培养乳腺组织中，研究了催乳素（PRL）对脂蛋白脂肪酶（LPL）活性和LPL mRNA水平的体外作用。小鼠乳腺组织最初在含有1微克/毫升胰岛素和10^(-7)摩尔/升皮质醇的M199培养基中孵育24小时。随后用1微克/毫升PRL处理组织，24小时后肝素可释放的LPL（hrLPL）活性增加了76%。添加PRL后16小时检测到LPL活性显著增加，但在更早的时间未检测到。100纳克/毫升的PRL引起LPL活性的最大刺激。当采用Northern杂交技术时，还发现PRL增加了LPL mRNA的组织含量；在使用50纳克/毫升及以上PRL浓度处理6小时后最初检测到这种效应。特异性研究表明，只有催乳激素能刺激培养乳腺组织中的LPL活性和LPL mRNA积累。PRL对用该激素培养超过6小时的乳腺组织中的ATP柠檬酸裂解酶活性也有小幅度（增加25%）但显著的影响。
