Prolactin binding in rat mammary gland during pregnancy and lactation

Holcomb, Henry H.; Costlow, Mark E.; Buschow, Robert A.; McGuire, William

doi:10.1016/0304-4165(76)90112-4

Cited by 62 publications

(27 citation statements)

References 13 publications

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“…The long form, Prlr-l, and short form, Prlr-s, are the predominant forms with Prl-l being the principal transducer of the lactogenic signal through the Jak2/ Stat5 pathway during lactation (Ormandy et al 2003). PRL upregulates PRLR as a Wrst step in the signal transduction process of the hormone (Holcomb et al 1976;McNeilly and Friesen 1977). Inhibition of prolactin secretion with bromocryptine markedly reduces lipid synthesis and decreases abundance of Acaca and Fasn in rat mammary gland (Barber et al 1997;Ros et al 1990).…”

Section: Introductionmentioning

confidence: 98%

“…Our recent study revealed that the aberrant PRL proWle during the peripartum period in HG-exposed dams was accompanied by a decrease in Prlr mRNA abundance (Patel et al 2007). In view of the documented eVects of lactogenic hormones on induction of PRLR expression (Holcomb et al 1976;McNeilly and Friesen 1977;Mizoguchi et al 1997;Phillips et al 1997Phillips et al , 1999Sakai et al 1994) and reported downregulation of PRLR transcripts in HG-exposed animals, we hypothesized that supplementation with either PRL or GC would correct the suppressed levels of PRLR transcripts and abrogate the HG-induced eVect(s) on lipogenesis and result in increased neonatal survival. Therefore, the objective of this study was to determine if PRL or GC supplementation would prevent or attenuate the HG eVects on periparturient dam metabolism.…”

Section: Introductionmentioning

confidence: 98%

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Lipogenesis impaired in periparturient rats exposed to altered gravity is independent of prolactin and glucocorticoid secretion

et al. 2008

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Perturbed prolactin (PRL) secretion and concomitant downregulation of PRL receptor (PRLR) in periparturient dams exposed to altered gravity are linked to aberrant lipogenesis and reduced neonatal survival. PRL and glucocorticoids (GC) are known to modulate PRLR expression. We hypothesized that improving levels of PRLR would mitigate the increased gravity [hypergravity (HG)]-induced effects of impaired mammary lipogenesis and increase neonatal survival. The objective of this study was to determine if prepartum PRL or GC supplementation would override the HG-induced repression of PRLR along with lipogenic genes and increase tissue fatty acid synthesis. Pregnant rats were exposed to either 2g (HG) or kept at 1g (control) from day 11 of gestation (G11) through Postnatal day 1 (P1). HG exposed rats were supplemented with either PRL or corticosterone or a placebo from G13 to P1. On P1, mammary, liver and adipose tissues were collected to measure glucose incorporation into lipids and mRNA abundance of PRL long and short form receptors (Prlr-l, Prlr-s), glucocorticoid receptor (Nr3c1), Acetyl CoA carboxylase-alpha (Acaca), fatty acid synthase (Fasn), lipoprotein lipase (Lpl), Sterol Regulatory Element Binding Protein-1 (Srebp1) and protein kinase B (Akt1) genes by quantitative polymerase chain reaction (qPCR). PRL and GC supplementation had a limited effect on lipogenesis in the three tissues of HG group likely due to their inability to increase abundance of key down-regulated genes, including Prlr-l and Nr3c1. There was no difference in the abundance of genes coding for milk proteins or those associated with milk fat globule formation and secretion. These data suggest that reduced lipogenesis in HG exposed dams is independent of PRL and GC secretion but may be associated with dysregulation of multiple metabolic regulators at the level of mRNA expression.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

Lipogenesis impaired in periparturient rats exposed to altered gravity is independent of prolactin and glucocorticoid secretion

et al. 2008

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“…Nevertheless, it is the same order of magnitude as in other mammalian receptors-e.g., oPRL receptors in the rat mammary gland (17) and FSH receptors in the rat testis (18). The competition experiments with unlabeled hCG and other hormones suggest that binding of gonadotropin to P. maltophilia is not simply an ionic interaction between cationic ligands and the anionic lipopolysaccharide complex of the bacterial outer membrane (19).…”

Section: Methodsmentioning

confidence: 99%

Specific gonadotropin binding to Pseudomonas maltophilia.

Richert¹,

Ryan²

1977

Proc. Natl. Acad. Sci. U.S.A.

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Binding of 1251-labeled human chorionic gonadotropin to Pseudomonas maltophifia is dependent on time, temperature, and pH and the binding to this procaryotic species is hormone-specific and saturable. The equilibrium dissociation constant is 2.3 X 10-9 M. There are no cooperative interactions between binding sites (Hill coefficient, 1.05 Stock cultures were maintained on eosin-methylene blue agar plates and nutrient agar slants at room temperature. For binding studies, several small (1-2 mm) granular colonies were inoculated into a sterile tube containing 5 ml of trypticase soy broth, pH 7.4. After overnight incubation at 300 in a shaking water bath, the culture was transferred to a 2-liter sterile flask containing 500 ml of trypticase soy broth and grown to stationary phase at 30°in a shaking water bath (100 oscillations/ min).* Stationary phase cultures had an optical density (turbidity) at 625 nm of 3.5-9.0, depending on the bacterial strain. Although binding activity was tested twice a day during all phases of growth, maximal binding in P. maltophilia generally occurred within 48 hr after the culture reached stationary phase.Preparation of Bacterial Pellets for Binding Assays. Bacteria were harvested by centrifugation at 20,000 X g for 20 min at 40 and washed twice with an equivalent volume of 40 mM Tris-HCl, pH 7.4. The pellets were resuspended at a 10-fold concentration in 40 mM Tris-HCl, pH 7.4, containing 10% sucrose. These pellets could be stored at -700 for 6 months without appreciable loss of binding activity. For

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“…The presence of high levels of placental lactogen, particularly before abortion in the present system, makes it difficult to accurately determine the number of PRL-Rs due to the masking of PRL-R with the hormone [12]. Furthermore it is difficult to predict precisely the onset time of parturition in vivo.…”

Section: Discussionmentioning

confidence: 93%

“…At present, the time-dependent change in the number of PRL-Rs especially before parturition remains unknown, since it is difficult to predict precisely the onsettime of parturition in viva. The changes in mammary gland functions are examined by means of the ovariectomy-initiated lactation system as a model of lactogenesis [10][11][12][13][14]. It is difficult to determine the actual number of PRL-Rs by the PRL-binding assay during mid-to late pregnancy, since most PRL-Rs are occupied with placental lactogen at high levels [12], but the determination of the PRL-R mRNA level itself is slightly affected by the presence of placental lactogen.…”

Section: Introductionmentioning

confidence: 99%

Acute Expression of the PRL Receptor Gene after Ovariectomy in Midpregnant Mouse Mammary Gland.

et al. 1996

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Abstract.In order to examine the time-dependent expression of the PRL receptor (PRL-R) gene at lactogenesis, the level of PRL-R mRNA was determined following ovariectomy in pregnant mouse mammary gland. Following reverse transcription, the quantity of mRNA was measured by the competitive polymerase chain reaction. The casein (a 22000 molecular weight component) mRNA level was measured as a marker for milk synthesis. Following ovariectomy, the onset of abortion occurred mostly at 22-23 h and the level of casein mRNA began to increase at 12 h. The long and short forms of PRL-R mRNAs were detected in a molar ratio of 1:0.2 on day 12 of pregnancy. Eight h after ovariectomy, the long form of PRL-R mRNA began to increase, showing a bell-shaped profile with the highest peak at 16 h. The short form of PRL-R mRNA was at low levels and remained constant. The levels of the long form of PRL-R mRNA decreased similarly in the presence and absence of foster pups from 24 to 48 h. Conversely, casein mRNA were maintained at high levels by supplying foster pups. The level of the long form of PRL-R mRNA reached a maximum prior to abortion. The present experiments demonstrated that the acute expression of the PRL-R gene occurred in the mammary gland at lactogenesis.

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Prolactin binding in rat mammary gland during pregnancy and lactation

Cited by 62 publications

References 13 publications

Lipogenesis impaired in periparturient rats exposed to altered gravity is independent of prolactin and glucocorticoid secretion

Lipogenesis impaired in periparturient rats exposed to altered gravity is independent of prolactin and glucocorticoid secretion

Specific gonadotropin binding to Pseudomonas maltophilia.

Acute Expression of the PRL Receptor Gene after Ovariectomy in Midpregnant Mouse Mammary Gland.

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