Biomedical subjects

Julie Lafond

Publications and source records attributed to Julie Lafond.

At least 19 recordsLinked to original sources

PubMed2006

Differential expression of glucose transporters in rabbit placenta: effect of hypercholesterolemia in dams.

Low birth weight is observed in rabbit offspring when maternal hypercholesterolemia is induced during gestation, but the related etiology is still unknown. Glucose is one of the most important substances during fetal development, and defect in glucose supply to fetus was related to pathophysiological mechanisms in intrauterine growth restriction. Thus, the aim of this work was to evaluate the impact of maternal hypercholesterolemia during rabbit gestation on the glucose metabolism and the routing of glucose transporters (SLC2 and SLC5 [previously known as GLUT and SGLT]) in placenta. In this study, maternal and offspring serum levels of glucose and insulin were evaluated for control and hypercholesterolemic groups, and the mRNA and protein expressions of placental SLCs were quantified by real-time RT-PCR and Western immunoblot, respectively. Our data demonstrate that maternal hypercholesterolemia during gestation: 1) induces offspring hypoglycemia; 2) does not modify the genetic and protein expressions of SLC2A1 and SLC2A4 (previously GLUT1 and GLUT4) in total placental extract; 3) downregulates the placental SLC5A1 (previously SGLT1) protein expression without affecting its mRNA levels; 4) impairs the translocation of SLC2A1 but not SLC2A4 from cytoplasmatic pool to the cell membrane surface. Then we assume that reduction of offspring birth weight in presence of maternal hypercholesterolemia may be related to the offspring's hypoglycemia and the reduction of the cell surface expression of placental SLC2A1.

Animals↗

PubMed2006

Src family kinases play multiple roles in differentiation of trophoblasts from human term placenta.

Tyrosine phosphorylation plays a major role in controlling many biological processes in different cell types. Src family kinases (SFKs) are one of the most studied groups of tyrosine kinases and can mediate a variety of signalling pathways. However, little is known about the expression of SFKs in human term placenta and their implication in trophoblast differentiation. Therefore, we examined the expression profile of SFK members over time in culture and their implication in differentiation. In vitro, freshly isolated cytotrophoblast cells, cultured in 10% fetal bovine serum (FBS), spontaneously aggregate and fuse to form multinucleated cells that resemble phenotypically mature syncytiotrophoblasts, that concomitantly produce human chorionic gonadotropin (hCG) and human placental lactogen (hPL). In this study, we showed that trophoblasts expressed all SFK members and some of them are expressed as different splice variants. Moreover, using real-time PCR, this study showed two different expression profiles of SFKs in human trophoblasts during culture. In addition, the protein level and phosphorylation status of Src were evaluated using specific antibodies. Src was rapidly phosphorylated at Tyr-416 and dephosphorylated at Tyr-527 after FBS addition. Surprisingly, inhibition of SFKs by 4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo[3,4-d] pyrimidine (PP2) or herbimycin A had different effects on trophoblast differentiation. While herbimycin A inhibited morphological and hormonal differentiation, PP2 stimulated hormonal differentiation and inhibited cell adhesion and spreading with no effect on cell fusion. In summary, this study showed that SFKs play different roles in trophoblast differentiation, probably depending on SFK members activated. Thus, this study increases our knowledge and understanding of pathology related to impaired trophoblast differentiation such as pre-eclampsia and trophoblast neoplasm.

Benzoquinones↗

PubMed2006

Calcium homeostasis in human placenta: role of calcium-handling proteins.

The human placenta is a transitory organ, representing during pregnancy the unique connection between the mother and her fetus. The syncytiotrophoblast represents the specialized unit in the placenta that is directly involved in fetal nutrition, mainly involving essential nutrients, such as lipids, amino acids, and calcium. This ion is of particular interest since it is actively transported by the placenta throughout pregnancy and is associated with many roles during intrauterine life. At term, the human fetus has accumulated about 25-30 g of calcium. This transfer allows adequate fetal growth and development, since calcium is vital for fetal skeleton mineralization and many cellular functions, such as signal transduction, neurotransmitter release, and cellular growth. Thus, there are many proteins involved in calcium homeostasis in the human placenta.

Animals↗

PubMed2005

ERK1/2 and p38 regulate trophoblasts differentiation in human term placenta.

Mitogen-activated protein kinases (MAPKs) control many cellular events from complex programmes, such as embryogenesis, cell differentiation and proliferation, and cell death, to short-term changes required for homeostasis and acute hormonal responses. However, little is known about expression and activation of classical MAPKs, extracellular signal-regulated kinase1/2 (ERK1/2) and p38 in human placenta. Therefore, we examined the expression of ERK1/2 and p38 in trophoblasts from human term placenta, and their implication in differentiation. In vitro, freshly isolated cytotrophoblast cells, cultivated in 10% fetal bovine serum (FBS), spontaneously aggregate and fuse to form multinucleated cells that phenotypically resemble mature syncytiotrophoblasts, that concomitantly produce human chorionic gonadotropin (hCG) and human placental lactogen (hPL). This study shows that the level of ERK1/2 and p38 decreases with increasing days of culture, to reach an undetectable level after 5 days of culture. Moreover, pretreatment of cells with an ERK1/2-specific inhibitor (PD98059) and/or a p38-specific inhibitor (SB203580) suppressed trophoblast differentiation. Our results also demonstrate that the p38 pathway is highly solicited as compared to the ERK1/2 pathway in the differentiation process. Furthermore, ERK1/2 and p38 are rapidly activated upon addition of FBS, but the activation of p38 is delayed compared to that of ERK1/2. In summary, this study showed that ERK1/2 and p38 pathways are essential to mediate initiation of trophoblast differentiation.

Adult↗

PubMed2005

Calbindin-D28k (CaBP28k) identification and regulation by 1,25-dihydroxyvitamin D3 in human choriocarcinoma cell line JEG-3.

Calbindin-D28k (CaBP28k) is a cytosolic calcium (Ca2+)-binding protein expressed in tissues such as intestine, kidneys and placenta. This protein is thought to be involved in Ca2+ homeostasis. While it is well known that CaBP28k is influenced by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] in the intestine and kidneys, nothing is known regarding the regulation of this protein in trophoblasts of human placenta. We used JEG-3 syncytiotrophoblast-like carcinoma cell line to study the regulation of CaBP28k in correlation with 1,25(OH)2D3 receptor (VDR) following 1,25(OH)2D3 treatments. Our data demonstrated for the first time that both CaBP28k mRNA and protein were highly induced by the addition of 1,25(OH)2D3 in dose-dependent manner. Moreover, the increase and subsequent decrease in the expression of CaBP28k and VDR mRNAs indicates the transient nature of the changes in gene expression in response to 1,25(OH)2D3. This is in contrast with the temporal pattern of increasing protein for CaBP28k and VDR. We also showed that new RNA and protein syntheses are required for 1,25(OH)2D3-induced upregulation of CaBP28k. Furthermore, a 25-carboxylic ester analogue of 1,25(OH)2D3, ZK159222, used as an antagonist of 1,25(OH)2D3 signaling confirmed that indeed 1,25(OH)2D3 was implicated in the induction of CaBP28k. These novel findings are a contribution to the processes that drive CaBP28k expression regulation in human placenta.

Calbindin 1↗

PubMed2005

Expression of cFABP and PPAR in trophoblast cells: effect of PPAR ligands on linoleic acid uptake and differentiation.

Throughout gestation, fetal growth depends, in part, on placental transfer of maternal essential fatty acid (EFA) and long-chain polyunsaturated fatty acid. All fatty acid (FA) can cross lipid bilayer by simple diffusion, such as those in the syncytiotrophoblasts, the multinucleated, terminally differentiated trophoblast cells. The trophoblasts differentiation process is accompanied by an increase of human chorionic gonadotropin (hCG) secretion and an inhibition of Human Achaete-Scute Homologue-2 expression (Hash-2). Furthermore, a number of FA-binding proteins (FABPs) have been identified in membrane and cytoplasm of mammalian cells, which are thought to facilitate the transfer of FA across membranes and their intracellular channeling. Thus, the aim of this study was to investigate the implication of cFABPs in linoleic acid (LA) uptake by human trophoblast cells according to differentiation. Moreover, since peroxisome proliferator-activated receptor (PPARs) regulate the expression of cFABP and play an important role in trophoblast cells differentiation, the effects of PPARs ligands are verified on cFABP expression and differentiation. Herein, we reported the increase of the expression of liver and heart FABP (L- and H-FABP) upon differentiation of trophoblast cells, an inhibition of PPAR alpha and beta, while PPAR gamma levels remains unchanged. The nonselective peroxisome-proliferating agents, bezafibrate and LA, impaired trophoblast differentiation, and reduced L- and H-FABP expression. Furthermore, cobalt, a chemical agent known to mimic hypoxia, inhibits trophoblast cells differentiation and diminishes H-, L-FABP and PPARs expression. Finally, both treatments show no influence on LA uptake by trophoblast cells. In conclusion, this study showed that there is no correlation between the expression of H- and L-FABP and LA uptake by trophoblast cells and that bezafibrate and LA greatly impaired trophoblast cells differentiation.

Basic Helix-Loop-Helix Proteins↗

PubMed2005

Calcium channels, transporters and exchangers in placenta: a review.

Calcium (Ca2+) entry in cells is crucial for development and physiology of virtually all cell types. It acts as an intracellular (second) messenger to regulate a diverse array of cellular functions, from cell division and differentiation to cell death. Among candidates for Ca2+ entry in cells are-voltage-dependant Ca2+ channels (VDCCs), transient receptor potential (TRP)-related Ca2+ channels and store-operated Ca2+ (SOC) channels. Plasma membrane Ca2+-ATPases (PMCA) and Na+/Ca2+ exchanger (NCX) are mainly responsible for Ca2+ extrusion. These different Ca2+channels/transporters and exchangers exhibit specific distribution and physiological properties. During pregnancy, the syncytiotrophoblast layer of the human placenta transfers as much as 30 g of Ca2+ from the mother to the fetus, especially in late gestation where Ca2+ transport through different channels must increase in response to the demands of accelerating bone mineralization of the fetus. The identification and characterization of the different Ca2+ channels/transporters and exchangers on the brush-border membrane (BBM) facing the maternal circulation, and the basal plasma membrane (BPM) facing the fetal circulation; placental membrane of the syncytiotrophoblasts have been the focus of numerous studies. This review discusses current views in this field regarding localization and functions during transcellular Ca2+ entry and extrusion from cells particularly in the placenta.

Animals↗

PubMed2005

Thyroid hormones in pregnancy in relation to environmental exposure to organochlorine compounds and mercury.

Polychlorinated biphenyls (PCBs), chlorinated pesticides, and mercury are global environmental contaminants that can disrupt the endocrine system in animals and humans. However, there is little evidence that they can interfere with endocrine status in pregnant women and neonates at low levels of exposure. The aim of this study was to examine thyroid hormone levels during pregnancy and in cord blood in relation to blood concentrations of organochlorine compounds (OCs) and Hg in healthy women recruited during pregnancy. We found a significant negative correlation between maternal total triiodothyronine levels and three non-coplanar congeners (PCB-138, PCB-153, and PCB-180), three pesticides (p,p -DDE, cis-nanochlor, and hexachlorobenzene), and inorganic Hg independently, without any other changes in thyroid status. No significant relationships were observed between OCs and cord serum thyroid hormones. Cord serum free thyroxin was negatively correlated with inorganic Hg. These results suggest that at even low levels of exposure, persistent environmental contaminants can interfere with thyroid status during pregnancy.

Adolescent↗

PubMed2004

Low environmental contamination by lead in pregnant women: effect on calcium transfer in human placental syncytiotrophoblasts.

There is an extensive literature on the neurotoxic effects of lead (Pb) on the developing fetus; however, little is known about the mechanisms of action at low levels. Heavy metals are known to affect calcium (Ca2+) homeostasis through perturbation of Ca2+ channels and pumps and interference with protein kinase C (PKC) and Ca2+ binding protein (CaBP). During pregnancy, placental Ca2+ exchange is one of the most important mechanisms for fetal survival. This ion is an essential element for healthy fetal growth and development. The aim of the present study was to determine the influence of low maternal blood Pb levels on Ca2+ levels in serum and placenta and placental Ca2+ transfer. Blood samples (maternal and cord) and placental tissue were obtained at birth from 30 women residing in southwest Quebec. Total Ca2+ and Pb levels were measured in maternal and umbilical cord samples and placental tissue at term. The placentas were taken for trophoblast cell isolation and Ca2+ incorporation kinetic experiments. Data showed that Ca2+ in maternal blood did not influence Ca2+ uptake by syncytiotrophoblast. However, although maternal and cord blood Pb levels were low, maternal blood Pb concentration was significantly linked to a decrease in Ca2+ uptake by syncytiotrophoblast. This suggests that exposure to very levels of Pb significantly modifies Ca2+ transfer in syncytiotrophoblasts.

Adult↗

PubMed2004

Influence of a maternal cholesterol-enriched diet on [1-14C]-linoleic acid and L-[4, 5-3H]-leucine entry in plasma of rabbit offspring.

Fetal development requires an important entry of essential free fatty acids (EFFA) and essential amino acids (EAA) into the fetal circulation. We have reported that a 0.2% enriched-cholesterol diet (ECD) during rabbit gestation significantly reduces fetus weight compared to control diet. It is known that dietary linoleic acid deficiency, an EFFA, during the fetal development induces an important impair to the somatic development. Moreover, intrauterine growth retardation induced a reduction of the flux of leucine, an EAA, from maternal to fetal circulation. Therefore, we hypothesized that the administration of an ECD induces modifications of placental lipid composition concomitant alterations of the transfer of linoleic acid and leucine in fetal circulation. Quantification of placental lipids revealed that in the ECD group a reduction of total-cholesterol (TC) and free-cholesterol (FC) is observed, however an increased in FFA and phospholipids is noticed when compared to the control group. In placenta from the ECD group, the FC/ TC ratio is significantly reduced compared to the control group. In the ECD group, the liver shows an increase of TC, FC and FFA compared to the control group. However, the quantity of triacylglycerol present in the liver from the ECD is significantly reduced compared to the control group. To evaluate the placental transfer of some essential nutrients, intravenous injection of [1-14C]-linoleic acid or L-[4, 5-3H]-leucine to term rabbit (control and ECD group) were done. Two hours later, rabbits were euthanized and we collected placenta, livers and blood from dams and offspring. The concentrations of both radiolabeled molecules (linoleic acid and its esterified form or leucine) were higher in the plasma of ECD offspring than those found in offspring from control diet. Despite such alteration of placental lipid composition, linoleic acid and leucine transfer by the placenta was not compromised but rather increased.

Animals↗

PubMed2004

Evaluation of 3-hydroxy-3-methylglutaryl-COA-reductase, cholesterol-7alpha-hydroxylase and acyl-COA:cholesterol acyltransferase activities: alternative chromatographic methods to separate metabolites.

Alternative HPLC and solid-phase extraction column methods were developed to separate metabolites of enzymes involved in cholesterol metabolism in rabbit liver microsomes: hydroxyl-methylglutaryl-CoA reductase, cholesterol-7alpha-hydroxylase and acyl-CoA:cholesterol acyltransferase. A comparison method of thin-layer chromatography and solid-phase extraction column were assayed to separate substrate and metabolite of hydroxy-methylglutaryl-CoA reductase, whereas for cholesterol-7alpha-hydroxylase and acyl-CoA:cholesterol acyltransferase, this comparison was done between thin layer chromatography and HPLC. The results obtained by the new analytical chromatographic methods are not significantly different than those observed in literature. Moreover a larger percentage recovery was obtained for analysed metabolites. Our results demonstrate the reliability of these alternative chromatographic techniques and showed that they are valuable tools to precisely and rapidly measure the activity of those enzymes.

Animals↗

PubMed2004

Manganese levels during pregnancy and at birth: relation to environmental factors and smoking in a Southwest Quebec population.

Manganese (Mn) is both an essential element and a potent neurotoxin. Higher demand during pregnancy leads to increased blood levels. Previous studies have suggested that environmental factors may influence blood Mn levels. As part of a community-based survey of potentially toxic environmental contaminants among pregnant women, the objective of this exploratory study was to examine the Mn status in pregnant women and their newborns with respect to sociodemographic and environmental variables. Pregnant women from Southwest Quebec were recruited in the first or second trimester through the public health prenatal program Mn was analyzed in mother's blood at entry into the study, in the second trimester (for those who entered during the first trimester), and at delivery, as well as in umbilical cord blood and in placental tissue. Sociodemographic data and information about pregnancy were obtained by two questionnaires; the first was administered at study entry and the second a few weeks following birth. Results showed that mothers' Mn blood levels increased significantly during pregnancy and cord blood Mn levels were significantly higher than those for mothers' blood. There was no relation to age. Smokers had significantly lower Mn blood levels compared to nonsmokers at the second trimester. Those who lived in urban and/or agricultural areas had significantly higher levels compared to those who lived in small villages. Those who reported pesticide spraying less than 1 km from their house likewise had significantly higher levels compared to the others. These findings suggest that lifestyle and environmental factors may interfere with the delicate balance and homeostatic mechanisms required to maintain Mn at optimal levels for physiological changes during pregnancy.

Adult↗

PubMed2004

Temporal variation of blood and hair mercury levels in pregnancy in relation to fish consumption history in a population living along the St. Lawrence River.

Fish consumption from the Great Lakes and the St. Lawrence River has been decreasing over the last years due to advisories and increased awareness of the presence of several contaminants. Methylmercury (MeHg), a well-established neurotoxicant even at low levels of exposure, bioaccumulates to differing degrees in various fish species and can have serious adverse effects on the development and functioning of the human central nervous system, especially during prenatal exposure. Most studies on MeHg exposure have focussed on high-level consumers from local fish sources, although mercury (Hg) is also present in fresh, frozen, and canned market fish. Moreover, little information exists on the temporal variation of blood and hair Hg in pregnant women, particularly in populations with low levels of Hg. The aim of the present study was to characterize the temporal variation of Hg during pregnancy and to investigate the relation between fish consumption from various sources prior to and during pregnancy and maternal cord blood and mother's hair Hg levels. We recruited 159 pregnant women from Southwest Quebec through two prenatal clinics of the Quebec Public Health System. All women completed two detailed questionnaires concerning their fish consumption (species and frequency) prior to and during pregnancy. The women also provided blood samples for all three trimesters of pregnancy and hair samples after delivery of up to 9 cm in length. Blood and hair Hg levels were analyzed by cold-vapor atomic-absorption and -fluorescence spectrometry methods, respectively. Results showed that maternal blood and hair Hg levels decreased significantly between the second and third trimesters of pregnancy. However, cord blood Hg was significantly higher than maternal blood at birth. Maternal hair was correlated with Hg blood concentration and was highly predictive of the organic fraction in cord blood. A strong dose relation was observed between the frequency of fish consumption before and during pregnancy and Hg exposure in mothers and newborns. Fish consumption prior to and during pregnancy explained 26% and 20% of cord blood Hg variance, respectively. For this population, detailed multivariate analyses showed that during pregnancy market fish (fresh, canned, and frozen) were more important sources of Hg exposure than were fish from the St. Lawrence River. These results should be taken into account for future advisories and intervention strategies, which should consider Hg levels in different species from all sources in order to maximize the nutritional input from fish and minimize the toxic risk.

Adolescent↗

PubMed2004

L-Carnitine transport in human placental brush-border membranes is mediated by the sodium-dependent organic cation transporter OCTN2.

Maternofetal transport of l-carnitine, a molecule that shuttles long-chain fatty acids to the mitochondria for oxidation, is thought to be important in preparing the fetus for its lipid-rich postnatal milk diet. Using brush-border membrane (BBM) vesicles from human term placentas, we showed that l-carnitine uptake was sodium and temperature dependent, showed high affinity for carnitine (apparent K(m) = 11.09 +/- 1.32 microM; V(max) = 41.75 +/- 0.94 pmol.mg protein(-1).min(-1)), and was unchanged over the pH range from 5.5 to 8.5. l-Carnitine uptake was inhibited in BBM vesicles by valproate, verapamil, tetraethylammonium, and pyrilamine and by structural analogs of l-carnitine, including d-carnitine, acetyl-d,l-carnitine, and propionyl-, butyryl-, octanoyl-, isovaleryl-, and palmitoyl-l-carnitine. Western blot analysis revealed that OCTN2, a high-affinity, Na(+)-dependent carnitine transporter, was present in placental BBM but not in isolated basal plasma membrane vesicles. The reported properties of OCTN2 resemble those observed for l-carnitine uptake in placental BBM vesicles, suggesting that OCTN2 may mediate most maternofetal carnitine transport in humans.

Carnitine↗

PubMed2003

Calbindin-D9k (CaBP9k) localization and levels of expression in trophoblast cells from human term placenta.

During pregnancy, the calcium (Ca(2+)) transport machinery of the placenta is solely responsible for the nutrient supply to the developing fetus, where active Ca(2+) transport occurs from the mother to the fetus. As part of a larger study to determine the role of Ca(2+) in placental transport in vivo, we questioned whether calbindin-D9k (CaBP9k), which is mainly expressed in duodenum, uterus, and placenta of several mammals, is present in cytotrophoblast cells and syncytiotrophoblasts of human term placenta. We were interested in this protein because of its potential importance in serving as an indicator of Ca(2+) availability and utilization in the placenta. Here, we demonstrated that CaBP9k transcript is present in both cell types, with a lower expression in cytotrophoblast cells as compared to syncytiotrophoblasts. Moreover, we showed by immunochemistry that CaBP9k protein was present in cytotrophoblast and syncytiotrophoblast placental tissue sections as well as in cultured cells. The occurrence of CaBP9k protein in trophoblast cells was further confirmed by Western blot analysis. Thus, these results indicate for the first time that CaBP9k is unequivocally expressed by trophoblast cells from human term placenta.

Animals↗

PubMed2003

Effects of low concentrations of organochlorine compounds in women on calcium transfer in human placental syncytiotrophoblast.

For most Canadians, food represents one of the major sources of environmental contaminants. Among them, organochlorine compounds (OCs) are known to affect calcium (Ca2+) homeostasis. They are neurotoxic by perturbation of Ca2+ channels and pumps, and they interfere with protein kinase C (PKC) and Ca2+ binding protein (CaBP). Ca2+ is an essential element to adequate fetal growth and development. The aim of the present study is to determine the relation between low environmental maternal exposure to OCs, such as polychlorinated biphenyls (PCB 153), Aroclor 1260, p,p'-dichlorodiphenyltrichloroethane (DDT) and p,p'-dichlorodiphenyl-dichloroethane (DDE), Ca2+ levels in serum and placenta, placental Ca2+ transfer, and newborn development. Total Ca2+ and OCs were measured in women's serum samples, as well as in umbilical cord's serum and placenta at term. Placentas were taken for trophoblast cells isolation and Ca2+ incorporation kinetic experiments. Our results were obtained from 30 pregnant women from the southwestern area of Quebec. Concentrations of Aroclor 1260, PCB 153, DDE, and DDT were respectively 6.1, 6.0, 3.1, and 2.9 times lower in the umbilical cord serum than in the mother's serum at term. In the placenta, DDE was accumulated at higher levels than other contaminants. A tendency towards an inverse relation was observed for in OCs found in three compartments and Ca2+ levels in maternal serum and in placental tissues. Maternal Ca2+ concentrations do not influence Ca2+ uptake by syncytiotrophoblast. Only DDE (>/=0.70 mug/l) in maternal serum significantly was associated with a small increase in Ca2+ uptake by syncytiotrophoblast. This study will help us determine if low OC contamination significantly modifies Ca2+ transfer in syncytiotrophoblast.

Biological Transport↗

PubMed2003

Impact of an enriched-cholesterol diet on enzymatic cholesterol metabolism during rabbit gestation.

An appropriate cholesterol homeostasis is vital for the maintenance and the optimal fetal development. The cholesterol is essential for the synthesis of progesterone and 17beta-estradiol, hormones that actively participate to sustain gestation. However, the administration of 0.2% enriched cholesterol diet (ECD) during rabbit gestation significantly increased the cholesterol blood profile (total-cholesterol, LDL, HDL, esterified-cholesterol and free-cholesterol) of dams and offspring, and induced a reduction of the offspring weight of 15% as compared to the control group. Enzymes involved in cholesterol metabolism (ACAT, HMG-CoA-reductase and cholesterol-7alpha-hydroxylase) are greatly influenced by cholesterol profile. We hypothesized that the administration of an ECD during rabbit gestation modifies the activity of those enzymes. Female rabbits (pregnant or not) were fed with a standard diet or an ECD. At term, livers (dams and offspring) and placentas were collected and ACAT, HMG-CoA-reductase and cholesterol-7alpha-hydroxylase activities were assayed. Our results demonstrate that gestation induced a reduction of ACAT activity (48.9%) in dam's liver and, an augmentation of HMG-CoA-reductase activity (142.4%) whereas it has no effect on cholesterol-7alpha-hydroxylase activity. The administration of the ECD has no additive effect on ACAT, but significantly reduced the HMG-CoA-reductase activity and cholesterol-7alpha-hydroxylase activity as compared with the pregnant control group. In placentas the ECD supplementation has an influence for HMG-CoA-reductase activity, where a 43% increased in observed. Any ACAT activity was detected in placenta and the ECD has no influence on the cholesterol-7alpha-hydroxylase activity. Whereas their offspring's liver present a reduction of ACAT and HMG-CoA-reductase activity. Gestation associated with ECD reduces significantly the HMG-CoA-reductase activity, decreasing the cholesterol synthesis, but placenta seems to compensate this effect by increasing its HMG-CoA-reductase activity.

Animals↗

PubMed2003

Calcium fluxes in human trophoblast (BeWo) cells: calcium channels, calcium-ATPase, and sodium-calcium exchanger expression.

Although placental transfer of maternal calcium (Ca(2+)) is a crucial process for fetal development, the biochemical mechanisms are poorly understood. In the current study, we have investigated the characteristics of Ca(2+) fluxes in relation with cell Ca(2+) homeostasis in the human placental trophoblast cell line BeWo. Time-courses of Ca(2+) uptake by BeWo cells displayed rapid initial entry (initial velocity (V(i)) of 3.42 +/- 0.35 nmol/mg protein/min) and subsequent establishment of a plateau. Ca(2+) efflux studies with (45)Ca(2+)-loaded cells also showed rapid declined of cell-associated (45)Ca(2+) with a V(i) of efflux (Ve(i)) of 3.30 +/- 0.08 nmol/mg protein/min. Further identification of membrane gates for Ca(2+) entry in BeWo cells was carried out. Expression of Ca(2+) transporter/channel CaT1 and L-type alpha(1S) subunit was showed by RT-PCR. However, mRNA for CaT2 channel and L-type alpha(1C) and alpha(1D) subunits were not revealed. Membrane systems responsible for intracellular Ca(2+) extrusion from BeWo cells were also investigated. Plasma membrane Ca(2+)-ATPases (PMCA) and Na/Ca exchangers (NCX) were detected by Western blot in BeWo cells. Expression of specific isoforms of PMCA and NCX was further investigated by RT-PCR. Messenger RNAs of four isoforms of PMCA (PMCA 1-4) were detected. The presence of messenger RNAs of two NCX isoforms (NCX1 and NCX3) was observed. Ca(2+) flux studies in Na-free incubation medium indicated that NCX played a minimal role in the cell Ca(2+) fluxes. Inorganic ions such as cadmium and manganese did not modify the Ca(2+) fluxes, however, barium increased cell-associated (45)Ca(2+) by, in part, by reducing radiolabel exit.

Calcium↗