Prolactin's Effects on Lipoprotein Lipase (LPL) Activity and on LPL mRNA Levels in Cultured Mouse Mammary Gland Explants

Hang, Junqi; Rillema, James A.

doi:10.3181/00379727-214-44083

Cited by 17 publications

(9 citation statements)

References 5 publications

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“…The possibilities are numerous. For example, PRL is known to regulate the expression of lipoprotein lipase (LPL) in the mammary gland and could thereby be affecting mammary gland development (Zinder et al 1974, Hang & Rillema 1997. The activity of LPL in the mammary gland, an enzyme important in fatty acid metabolism, rises during pregnancy and lactation (Zinder et al 1974, Jensen et al 1994.…”

Section: Discussionmentioning

confidence: 99%

Prolactin receptor expression in the epithelia and stroma of the rat mammary gland

Camarillo¹,

Thórdarson²,

Moffat³

et al. 2001

Journal of Endocrinology

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The importance of prolactin (PRL) in regulating growth and differentiation of the mammary gland is well known. However, it is not well established whether PRL acts solely on the mammary epithelia or if it can also directly affect the mammary stroma. To determine where PRL could exert its effects within the mammary gland, we investigated the levels of expression and the localization of the PRL receptor (PRLR) in the epithelia and stroma of the rat mammary gland at different physiological stages. For these studies, we isolated parenchymal-free 'cleared' fat pads and intact mammary glands from virgin, 18-daypregnant and 6-day-lactating rats. In addition, intact mammary tissues were enzymatically digested to obtain epithelial cells, free of stroma. The mammary tissues, intact gland, stroma and isolated epithelia, were then used for immunocytochemistry, protein extraction and isolation of total RNA. PRLR protein was detected in tissues using specific polyclonal antisera (PRLR-l) by immunocytochemistry and Western blot analysis. Messenger RNA for PRLR was measured by ribonuclease protection assay. Immunocytochemistry and Western blots with the PRLR-1 antisera detected PRLR in wild-type rat and mouse tissues, whereas the receptor protein was absent in tissues from PRLR gene-deficient mice. PRLR was found to be present both in the epithelia and stroma of mammary glands from virgin, pregnant and lactating rats, as determined by immunocytochemistry and Western blotting. Western blots revealed the predominance of three bands migrating at 88, 90 and 92 kDa in each of the rat mammary samples. These represent the long form of the PRLR. During pregnancy and lactation, PRLR protein increased in the epithelial compartment of the mammary gland but did not change within the stromal compartment at any physiological stage examined. We also found PRLR mRNA in both the epithelia and stroma of the mammary gland. Again, the stroma contained lower levels of PRLR mRNA compared with the epithelia at all physiological stages examined. Also, the PRLR mRNA levels within the stroma did not change significantly during pregnancy or lactation, whereas PRLR mRNA within the epithelia increased twofold during pregnancy and fourfold during lactation when compared with virgin rats. We conclude from this study that PRLR is expressed both in the stromal and epithelial compartment of the mammary gland. This finding suggests PRL may have a direct affect on the mammary stroma and by that route affect mammary gland development.

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Section: Discussionmentioning

confidence: 99%

Prolactin receptor expression in the epithelia and stroma of the rat mammary gland

Camarillo¹,

Thórdarson²,

Moffat³

et al. 2001

Journal of Endocrinology

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“…Besides hyperinsulinemia and the high insulin sensitivity in mammary glands during pregnancy [11], prolactin may also be involved as a positive mediator of LPL in mammary gland, since its concentration raises around parturition [30] and enhances both LPL activity and mRNA in cultured mammary gland explants from mid-pregnant mice [31]. Although not studied in the diabetic pregnant rat, decreases in plasma prolactin levels have been reported in diabetic pregnant women [32].…”

Section: Discussionmentioning

confidence: 99%

Streptozotocin‐Induced Diabetes Decreases Mammary Gland Lipoprotein Lipase Activity and Messenger Ribonucleic Acid in Pregnant and Nonpregnant Rats

Blanco-Dolado

Martín-Hidalgo

Herrera

2001

Journal of Diabetes Research

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Diabetes mellitus is associated with a reduction of lipoprotein lipase (LPL) activity in adipose tissue and development of hypertriglyceridemia. To determine how a condition of severe insulin deficiency affects mammary gland LPL activity and mRNA expression during late pregnancy, streptozotocin (STZ) treated (40 mg/kg) and non-treated (control) virgin and 20 day pregnant rats were studied. In control rats, both LPL activity and mRNA were higher in pregnant than in virgin rats. When compared to control rats, STZ-treated rats, either pregnant or virgin, showed decreased LPL activity and mRNA content. Furthermore, mammary gland LPL activity was linearly correlated with mRNA content, and either variable was linearly correlated with plasma insulin levels. Thus, insulin deficiency impairs the expression of LPL in mammary glands, revealing the role of insulin as a modulator of the enzyme at the mRNA expression level.

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“…When needed, ROH is released from hepatic cells into plasma bound to retinol-binding protein (RBP4). Once in plasma, it associates with the stabilizing protein transthyretin (TTR), which decreases the renal clearance of vitamin A [49][50][51][52][53][54][55].…”

Section: Intertissue Flux and Metabolic Transformations Of Vitamin Amentioning

confidence: 99%

Role of Vitamin A in Mammary Gland Development and Lactation

et al. 2019

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Vitamin A (all-trans-retinol), its active derivatives retinal and retinoic acid, and their synthetic analogues constitute the group of retinoids. It is obtained from diet either as preformed vitamin A or as carotenoids. Retinal plays a biological role in vision, but most of the effects of vitamin A are exerted by retinoic acid, which binds to nuclear receptors and regulates gene transcription. Vitamin A deficiency is an important nutritional problem, particularly in the developing world. Retinol and carotenoids from diet during pregnancy and lactation influence their concentration in breast milk, which is important in the long term, not only for the offspring, but also for maternal health. In this study, we review the role of vitamin A in mammary gland metabolism, where retinoid signaling is required not only for morphogenesis and development of the gland and for adequate milk production, but also during the weaning process, when epithelial cell death is coupled with tissue remodeling.

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Prolactin's Effects on Lipoprotein Lipase (LPL) Activity and on LPL mRNA Levels in Cultured Mouse Mammary Gland Explants

Cited by 17 publications

References 5 publications

Prolactin receptor expression in the epithelia and stroma of the rat mammary gland

Prolactin receptor expression in the epithelia and stroma of the rat mammary gland

Streptozotocin‐Induced Diabetes Decreases Mammary Gland Lipoprotein Lipase Activity and Messenger Ribonucleic Acid in Pregnant and Nonpregnant Rats

Role of Vitamin A in Mammary Gland Development and Lactation

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