Human placental lactogen induces CYP2E1 expression via PI 3-kinase pathway in female human hepatocytes.

The state of pregnancy is known to alter hepatic drug metabolism. Hormones that rise during pregnancy are potentially responsible for the changes. Here we report the effects of prolactin (PRL), placental lactogen (PL), and growth hormone variant (GH-v) on expression of major hepatic cytochromes P450 expression and a potential molecular mechanism underlying CYP2E1 induction by PL. In female human hepatocytes, PRL and GH-v showed either no effect or small and variable effects on mRNA expression of CYP1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1, 3A4, and 3A5. On the other hand, PL increased expression level of CYP2E1 mRNA with corresponding increases in CYP2E1 protein and activity levels. Results from hepatocytes and HepaRG cells indicate that PL does not affect the expression or activity of HNF1α, the known transcriptional activator of basal CYP2E1 expression. Furthermore, transient transfection studies and Western blot results showed that STAT signaling, the previously known mediator of PL actions in certain tissues, does not play a role in CYP2E1 induction by PL. A chemical inhibitor of PI3-kinase signaling significantly repressed the CYP2E1 induction by PL in human hepatocytes, suggesting involvement of PI3-kinase pathway in CYP2E1 regulation by PL. CYP2E1-humanized mice did not exhibit enhanced CYP2E1 expression during pregnancy, potentially because of interspecies differences in PL physiology. Taken together, these results indicate that PL induces CYP2E1 expression via PI3-kinase pathway in human hepatocytes.

Growth restricting effects of a single course of antenatal betamethasone treatment and the role of human placental lactogen.

UNLABELLED: Betamethasone (BET) is a widely used treatment for women who are at high risk of preterm delivery. In sheep, BET-induced growth restriction was found to be associated with reduced placenta lactogen (PL), a key regulator of fetal growth. We therefore hypothesized that also in humans a single course of BET administration is associated with a reduction of PL, associated with a deceleration in fetal growth. OBJECTIVE: To investigate effects of a single course of antenatal BET in humans on birth weight and PL. METHODS: Women exposed to BET (2 × 12 mg; n = 44) with normally grown fetuses between 23 + 5 and 34 + 0 wks (weeks + days of gestation) who delivered between 23 + 5 to 42 + 0 wks were compared to gestational age-matched controls (n = 49). Maternal gestational blood samples were obtained before, during and after BET treatment and at the time of birth. MAIN OUTCOME MEASURES: BET effects on fetal anthropometrics, placental morphometry and placental PL-protein and maternal plasma levels. RESULTS: The mean duration of days between BET administration and birth was 52 days. BET treatment was associated with decreased birth weight (-18.2%), head circumference (-8.6%), body length (-6.0%), and placental width (-5.5%), as compared to controls. These changes were irrespective of possible maternal confounders (gestational age at birth, maternal age, maternal BMI gain during pregnancy, smoking etc.). However, neither PL-plasma levels within 48 h after BET treatment nor placental PL-protein levels and maternal plasma levels at birth were changed after BET treatment. In central regions of the placenta, BET treatment increased the circumference of syncytiotrophoblast nuclei by +4.7% and nucleus surface area by +9.4% compared to controls, but these changes were not related to placental PL-protein or maternal PL-plasma levels at birth. CONCLUSION: A single course of BET treatment was accompanied with reduced fetal growth, but this growth restricting effect was not associated with altered placental or maternal plasma PL levels. Altered expression of PL appears not to be causal for BET-induced fetal growth restriction in the human.

Immunological distribution of the placental lactogene and IGF-1 receptor on free-chorionic villi of the newborns small for gestational age placentae

The aim of this study was observe differences in the immunological distribution of the placental lactogene and IGF-1 receptor on free-chorionic villi, between studied groups and to relate the neonatal diagnosis of PEG with morphometric and immunohystochemical characteristics of the placenta. A total of, twelve placentas from AEG newborn and twelve from PEG newborn were obtained from the Maternity Ward of Temuco, Chile. H&E, Alcian blue and Masson's trichromic stains, as well as Hematoxilyn-PAS. In the immunoperoxidase technique, were used: 1) placental lactogen (polyclonal, dilution 1:200, NCL-PLP, Novocastra) 2) Insuline-1 like growth factor (monoclonal, dilution 1:200, NCL-GHR, Novocastra). Differences between PEG and AEG placentae in the immnunostaing for placental lactogen and IGF-1 receptor in the sincitial throphoblast were not observed.

El objetivo de este estudio fue observar diferencias en la distribución del lactogeno placentario y receptor del factor de crecimiento similar a la insulina, entre placentas de recién nacidos normales para la edad gestacional AEG y pequeños para la edad gestacional PEG. Un total de 12 placentas de recién nacidos AEG y 12 PEG obtenidas de la maternidad del Hospital de Temuco, Chile fueron procesadas con técnicas histológicas H&E, azul de Alcián y un método de tinción tricrómico. La técnica de inmunoperoxidasa utilizada fue: 1) lactogeno placentario (pohclonal, dilución 1:200, NCL-PLP, Novocastra) 2) Factor de crecimiento similar a la insulina (monoclonal, dilución 1:200, NCL-GHR, Novocastra). No se observaron diferencias en la distribución de lactogeno placentario ni factor de crecimiento similar a la insulina entre las placentas provenientes de recién nacidos pequeños para la edad gestacional y adecuados para la edad gestacional.

Beta-cell failure as a complication of diabetes.

Type 2 diabetes mellitus is a complex disease characterized by beta-cell failure in the setting of insulin resistance. In early stages of the disease, pancreatic beta-cells adapt to insulin resistance by increasing mass and function. As nutrient excess persists, hyperglycemia and elevated free fatty acids negatively impact beta-cell function. This happens by numerous mechanisms, including the generation of reactive oxygen species, alterations in metabolic pathways, increases in intracellular calcium and the activation of endoplasmic reticulum stress. These processes adversely affect beta-cells by impairing insulin secretion, decreasing insulin gene expression and ultimately causing apoptosis. In this review, we will first discuss the regulation of beta-cell mass during normal conditions. Then, we will discuss the mechanisms of beta-cell failure, including glucotoxicity, lipotoxicity and endoplasmic reticulum stress. Further research into mechanisms will reveal the key modulators of beta-cell failure and thus identify possible novel therapeutic targets. Type 2 diabetes mellitus is a multifactorial disease that has greatly risen in prevalence in part due to the obesity and inactivity that characterize the modern Western lifestyle. Pancreatic beta-cells possess the potential to greatly expand their function and mass in both physiologic and pathologic states of nutrient excess and increased insulin demand. beta-cell response to nutrient excess occurs by several mechanisms, including hypertrophy and proliferation of existing beta-cells, increased insulin production and secretion, and formation of new beta-cells from progenitor cells [1, 2]. Failure of pancreatic beta-cells to adequately expand in settings of increased insulin demand results in hyperglycemia and diabetes. In this review, we will first discuss the factors involved in beta-cell growth and then discuss the mechanisms by which beta-cell expansion fails and leads to beta-cell failure and diabetes (Fig. 1).

Growth factors and beta cell replication.

Recent studies have demonstrated that human islet allograft transplantation can be a successful therapeutic option in the treatment of patients with Type I diabetes. However, this impressive recent advance is accompanied by a very important constraint. There is a critical paucity of pancreatic islets or pancreatic beta cells for islet transplantation to become a large-scale therapeutic option in patients with diabetes. This has prompted many laboratories around the world to invigorate their efforts in finding ways for increasing the availability of beta cells or beta cell surrogates that potentially could be transplanted into patients with diabetes. The number of studies analyzing the mechanisms that govern beta cell proliferation and growth in physiological and pathological conditions has increased exponentially during the last decade. These studies exploring the role of growth factors, intracellular signaling molecules and cell cycle regulators constitute the substrate for future strategies aimed at expanding human beta cells in vitro and/or in vivo after transplantation. In this review, we describe the current knowledge on the effects of several beta cell growth factors that have been shown to increase beta cell proliferation and expand beta cell mass in vitro and/or in vivo and that they could be potentially deployed in an effort to increase the number of patients transplanted with islets. Furthermore, we also analyze in this review recent studies deciphering the relevance of these specific islet growth factors as physiological and pathophysiological regulators of beta cell proliferation and islet growth.

The transcription factor PLA-1/SKN-1A is expressed in human placenta and regulates the placental lactogen-3 gene expression.

Here we report the selective expression of two POU transcription factor genes, PLA-1 and OCT-1, in human placenta and choriocarcinoma cell lines JAR, JEG-3 and BeWo. Pla-1 protein binds to a POU-consensus DNA sequence in the human placental lactogen-3 (PL-3) promoter and it is capable of trans-activating its transcription up to 18-fold. Other tissue-specific or ubiquitous POU transcription factors such as Pit-1/GHF-1 or Oct-1 showed none or low levels of trans-activation of the PL-3 promoter. In addition, we identified an unique and highly charged region in the N-terminal portion of Pla-1 protein required for full trans-activation of the PL-3 promoter.

Endocrinology of lactation.

The endocrine control of lactation is one of the most complex physiologic mechanisms of human parturition. Mammogenesis, lactogenesis, galactopoiesis, and galactokinesis are all essential to assure proper lactation. Prolactin is the key hormone of lactation and seems to be the single most important galactopoietic hormone. Oxytocin, serotonin, opioids, histamine, substance P, and arginine-leucine modulate prolactin release by means of an autocrine/paracrine mechanism, whereas estrogen and progesterone hormones can act at the hypothalamic and adenohypophysial levels. Human placental lactogen and growth factors play an essential role to assure successful lactation during pregnancy. Oxytocin is the most powerful galactokinetic hormone.

Roles of prolactin and related members of the prolactin/growth hormone/placental lactogen family in angiogenesis.

Prolactin, growth hormone and placental lactogen are members of a family of polypeptide hormones which share structural similarities and biological activities. Numerous functions have been attributed to these hormones, among which stand out their recently discovered effects on angiogenesis, the process by which new blood vessels are formed from the pre-existing microvasculature. Prolactin, growth hormone and placental lactogen, along with two non-classical members of the family, proliferin and proliferin-related protein, can act both as circulating hormones and as paracrine/autocrine factors to either stimulate or inhibit various stages of the formation and remodeling of new blood vessels, including endothelial cell proliferation, migration, protease production and apoptosis. Such opposing actions can reside in similar but independent molecules, as is the case of proliferin and proliferin-related protein, which stimulate and inhibit angiogenesis respectively. The potential to exert opposing effects on angiogenesis can also reside within the same molecule as the parent protein can promote angiogenesis (i.e. prolactin, growth hormone and placental lactogen), but after proteolytic processing the resulting peptide fragment acquires anti-angiogenic properties (i.e. 16 kDa prolactin, 16 kDa growth hormone and 16 kDa placental lactogen). The unique properties of the peptide fragments versus the full-length molecules, the regulation of the protease responsible for specific protein cleavage, the selective expression of specific receptors and their associated signal transduction pathways are issues that are being investigated to further establish the precise contribution of these hormones to angiogenesis under both physiological and pathological situations. In this review article, we summarize the known and speculative issues underlying the effects of the prolactin, growth hormone and placental lactogen family of proteins on angiogenesis, and address important remaining enigmas in this field of research.

Placental lactogen not growth hormone and prolactin regulates secretion of progesterone in vitro by the 40-45 day ovine corpus luteum of pregnancy.

The study was designed to compare the direct effect of three prolactin-like hormones on steroidogenesis of ovine luteal cells collected at day 40-45 of pregnancy. 100 ng/ml of ovine placental lactogen or 100 ng/ml of ovine growth hormone or 100 ng/ml of ovine prolactin were added to the media of luteal cell cultures. After 48 h incubation, all cultures were terminated and the media were frozen until further steroid analysis. To determine to what extent growth hormone (GH), prolactin (PRL) and lactogen (PL) regulate the activity of 3 beta-HSD, an enzyme involved in progesterone synthesis, the classical steroidal competitive inhibitor of 3 beta-HSD trilostane, was investigated for its effects on basal and GH-, PRL-, and PL-stimulated progesterone biosynthesis since there is a possibility that the luteotropic effect of these hormones are mediated via 3 beta-HSD. oPL resulted in an increase of progesterone secretion in a statistically significant manner, while GH or PRL had no effect on progesterone secretion. A decrease in progesterone secretion as an effect of 100 mM trilostane was observed in all culture types. An explanation for the luteotropic effect of PL and the lack of this effect for GH is that the GH receptor associates with a different molecule within the ovarian tissue and forms a heterodimeric receptor for PL, and the possibility that physiological effects of native oPL may be mediated through its binding to specific PL receptors, which have low affinities for oGH and oPRL.

Reassessment of the role of human placental lactogen in physiological non-pregnant and pathological conditions.

The recent demonstration of ectopic production of human placental lactogen (PL) in the human testis and ovary prompted us to reassess its role under non-pregnant physiological and pathological conditions. Possible physiological hPL concentrations and potential age-related changes in the sera of healthy young and elderly individuals (n = 75) selected according to the SENIEUR-protocol were investigated by a highly sensitive (detection limit: 2 pg/ml) and specific (cross-reactivity with prolactin and human growth hormone (hGH) of less than 0.001% and 0.0001%, respectively) monoclonal antibody-based time-resolved fluoroimmunoassay (IFMA) established in our laboratory. All individuals, even the aged probands (mean age: 72 +/- 3a), had hPL-levels below 20 pg/ml, in contrast to glycoprotein hormones, such as luteinizing hormone or human chorionic gonadotropin (hCG). To determine the significance of hPL as a tumour marker, serum samples of 12 testicular cancer patients with highly elevated levels of holo-hCG (mean: 42.490 ng/ml) at diagnosis were followed over 6-12 months and analysed with the hPL-IFMA. Elevation of hPL was seen in 10 patients, but the respective levels were 2-3 orders of magnitude smaller than those of holo-hCG and returned earlier to undetectable values. These in vivo data were compared to the hPL secretion pattern of the choriocarcinoma cell lines JAR and BeWo in vitro. In tissue culture supernatants of the two cell lines hPL was detected only in JAR cells, whereas both cell lines secreted holo-hCG. In conclusion, the fact that hPL is not physiologically present in peripheral blood but is produced ectopically in the human testis and ovary suggest auto/paracrine functions of this molecule. The significance of hPL as a tumour marker for patients with testicular cancer is limited as it provides no additional information to holo-hCG.

Lactogênese e reflexo ejecto-láctil / Lactogenesis and milk-ejection reflex

Apresenta-se uma revisäo näo exaustiva sobre os processos fisiológicos envolvidos com a produçäo e a ejeçäo de leite, bem como fatores que interferem em tais processos.

Interaction of mouse placental lactogens and androgens in regulating progesterone release in cultured mouse luteal cells.

Pituitary hormones are essential for the maintenance of the corpus luteum in the pregnant mouse during the first half of gestation. Thereafter, hormones from the placenta take over the luteotropic role of the pituitary hormones. Mouse placental lactogen-I (mPL-I) and mPL-II, two PRL-like hormones produced in the placenta, are probably necessary for the maintenance of the corpus luteum in the latter half of pregnancy. A culture system of luteal cells from pregnant mice was developed to investigate the role of hormones from the placenta that may be important for the function of the corpus luteum. Mice were killed on days 10, 14, and 18 of pregnancy, and the corpora lutea were excised from the ovaries and digested in 0.1% collagenase, 0.002% DNase for 1 h. The resulting luteal cell suspension was plated onto 96-well plates coated with fibronectin (1 x 10(5) cells/well) and cultured for 1-3 days. Medium was changed daily. The cells were treated with various concentrations and combinations of mPL-I, mPL-II, mouse PRL, androstenedione, dihydrotestosterone, 17beta-estradiol (E2), testosterone, hydroxyflutamide, cycloheximide, actinomycin D, and fadrozole to study the effects of these different treatments on progesterone (P4) production. The three lactogens (mPL-I, mPL-II, and mouse PRL) all stimulated the release of P4 from the luteal cells. The potency of the lactogens was similar and did not depend on the stage of pregnancy at which the luteal tissue was obtained. However, the responsiveness of the cells to all hormone-stimulated P4 release was gradually reduced the later in pregnancy the tissue was collected. Androgens also stimulated the release of P4 from the luteal cells, and when administered together, the lactogens and the androgens acted synergistically to stimulate P4 release. The androgens acted directly but not through conversion to E2, as determined by the findings that 1) the effects of the androgens could not be reproduced by E2 administration, 2) nonaromatizable androgen dihydrotestosterone was as effective as aromatizable androgens, and 3) aromatase inhibitor did not prevent the action of the androgens to stimulate the P4 release. The effect of the androgens on the P4 release was rapid, occurring within 15 min of hormone administration. It was not prevented by inhibitors of protein and RNA synthesis, and the intracellular androgen receptor antagonist hydroxyflutamide did not affect the androgen action. Therefore, the androgen effects were not mediated through the intracellular androgen receptor and de novo protein synthesis was not needed for androgen-stimulated P4 release.

Luteotropic actions of placental lactogens at midpregnancy in the mouse.

In this study the luteotropic activity of mouse placental lactogen I (mPL-I) at midpregnancy was assessed using in vivo and in vitro methodologies. Ovaries from 10-day pregnant mice were enzymatically dispersed and plated on fibronectin-coated wells in serum-free medium. The percentage of ovarian cells that stained for the presence of 3 beta-hydroxysteroid dehydrogenase activity was 24.4 +/- 2.7% at the time of plating and remained constant (26.1 +/- 5.0%) after a 20-h attachment period. Two types of 3 beta-hydroxysteroid dehydrogenase-staining cells, with distinct differences in size and morphology, were present in the culture. Large luteal cells (26-45 microns) were characterized by a small round nucleus and spherical shape with abundant cytoplasm. In contrast, small luteal cells (< 20 microns) were stellate, with little cytoplasm and a large oval nucleus. Basal progesterone secretion was maintained without a change in cellular DNA content and cell number for 168 h of culture. Treatment of ovarian cells with mPL-I (0.05-10 micrograms/ml) caused a dose-dependent increase in the progesterone concentration in the medium. The magnitude and time course of mPL-I-stimulated progesterone accumulation in culture were dependent on the time after plating that mPL-I treatment was initiated. The effects of mPL-II and mouse PRL (mPRL) on progesterone production were similar to those of mPL-I. The ability of sera from 10-, 14-, and 17-day pregnant mice to maintain progesterone production in bromocryptine-treated hysterectomized mice was also examined. Mice were hysterectomized on day 9 of pregnancy, and serum progesterone, mPL-I, mPL-II, and mPRL concentrations were measured 72 h later. Twice daily injections of 0.5 ml day 10 pregnancy serum maintained the circulating progesterone concentration at values not different from those present at the time of hysterectomy. In contrast, serum progesterone concentrations were not maintained in mice treated with serum of 14- or 17-day pregnant mice or with saline. Depletion of mPL-I from day 10 pregnancy serum by affinity chromatography on an anti-mPL-I column removed all luteotropic activity, as determined by the inability of this modified serum to maintain the serum progesterone concentration in bromocryptine-treated hysterectomized mice. A similar pool of day 10 pregnancy serum chromatographed on a nonspecific IgG control column did maintain progesterone production, but at somewhat lower concentrations than those present at the time of surgery. These studies offer direct evidence that mPL-I and mPL-II are luteotropic and support progesterone production at midpregnancy in the mouse.

Human placental lactogen infusions into the medial preoptic area stimulate maternal behavior in steroid-primed, nulliparous female rats.

The effects of central administration of human placental lactogen (hPL) on the onset of maternal behavior were measured in steroid-primed, adult ovariectomized, nulliparous rats. Rats were fitted with bilateral cannulas directed at the medial preoptic area (MPOA) and gonadectomized 1 week before being implanted sc with progesterone (P)-filled Silastic implants (treatment Day 1). On Day 11 P capsules were removed, and each female was implanted sc with a single estradiol (E2) capsule. On Days 11 to 13 animals were infused bilaterally with 40 ng of hPL/infusion or given 0.4 microliter vehicle. Subjects were given hormone or vehicle infusions five times during this period, twice each on Days 11 and 12 (1000 and 1600 hr) and once on Day 13 (1000 hr). Behavioral testing began on day 12 after the 1000 hr infusions and continued daily for 6 days. All females were injected sc twice daily with bromocriptine (2 mg/ke) to suppress endogenous PRL secretion from Day 11 to the completion of testing. The results showed that central infusions of hPL stimulated a fast onset of maternal behavior relative to controls. Latencies to display specific components as well as complete maternal behavior toward foster young were about 1 day in the hPL-treated group and 4 days in vehicle-infused controls. Infusions of hPL into the MPOA between 7.8 and 8.0 AP resulted in the fastest rate of onset of maternal behavior. These findings demonstrate that central infusion of a heterologous placental lactogen, hPL, is capable of stimulating maternal behavior may normally be brought about by exposure to placental lactogens as well as prolactin.

Participación de hormonas y factores reguladores de la implantación y el desarrollo de la unidad fetoplacentaria / Hormonal participation and regulating factors of implantation and the fetoplacentary unity development

Si bien el embrión tiene un programa genético de su propio desarrollo, para que se lleven a cabo el desarrollo y diferenciación embrionaria, así como la gestación normal, deben establecerse una serie de interacciones coordinadas entre el concepto y la madre, las cuales son mediadas por mensajeros químicos mediante mecanismo autocrinos, paracrinos y endocrinos. En el presente trabajo se analiza la participación de hormonas y factores réguladores de la implantación y el desarrollo de la unidad feto-placentaria

Somatolactogens, somatomedins, and immunity.

The neuroendocrine and immune systems participate as active partners in host homeostatic and defense mechanisms. This partnership involves a complex intercommunication system employing an array of shared ligands and receptors. Hormones of the somatolactogen family have marked influences on immune events in vivo, including the maintenance of lymphoid tissue cellularity, the promotion of DNA synthesis in these tissues, and the stimulation of a number of immune effector mechanisms. Both growth hormone and prolactin function to promote erythropoiesis and DNA synthesis in bone marrow precursors. Our results have shown that the somatolactogens and a member of the somatomedin family, IGF-I, are particularly effective in modulating the effector functions in phagocytic cells, including the production of reactive oxygen intermediates and tumor necrosis factor-alpha and the oxygen-dependent killing of bacteria. Evidence indicating a role of IGF-I in modulating immune functions is more recent but nonetheless compelling. Accumulated data suggest that somatolactogenic hormones, as well as one member of the somatomedins, are produced by cells of the immune system and can regulate local immune events. Although the molecular mechanisms by which the somatolactogens and somatomedins exert their effects on immune tissues are only now being explored, the pleiotropic nature of these effects suggests that these hormones participate at endocrine, paracrine, and perhaps autocrine sites of action.

Placental lactogen is a haemopoietic hormone.

The anaemia and thrombocytopenia of hypophysectomized (Hypox) rats could be corrected readily by daily treatment with human placental lactogen. Spontaneous DNA synthesis in the bone marrow of Hypox rats was grossly impaired, which was also normalized by placental lactogen. Human placental lactogen exerted a direct mitogenic effect on rat bone marrow cells in vitro. These results indicate that placental lactogen is a potent haemopoietic hormone.