The placenta in nutrition

Porcine Placenta Peptide Inhibits UVB-Induced Skin Wrinkle Formation and Dehydration: Insights into MAPK Signaling Pathways from In Vitro and In Vivo Studies

Excessive exposure to ultraviolet (UV) radiation from sunlight accelerates skin aging, leading to various clinical manifestations such as wrinkles, dryness, and loss of elasticity. This study investigated the protective effects of porcine placenta peptide (PPP) against UVB-induced skin photoaging. Female hairless SKH-1 mice were orally administered PPP for 12 weeks, followed by UVB irradiation. PPP significantly reduced wrinkle formation, improved skin moisture levels, and prevented collagen degradation. Mechanistically, PPP inhibited the expression of matrix metalloproteinases (MMPs) and upregulated collagen production. Moreover, PPP elevated hyaluronic acid levels, contributing to enhanced skin hydration. Additionally, PPP demonstrated antioxidant properties by increasing the expression of the antioxidant enzyme GPx-1, thereby reducing UVB-induced inflammation. Further molecular analysis revealed that PPP suppressed the activation of p38 MAP kinase and JNK signaling pathways, crucial mediators of UV-induced skin damage. These findings highlight the potential of porcine placental peptides as a natural and effective intervention against UVB-induced skin photoaging. The study provides valuable insights into the mechanisms underlying the protective effects of PPP, emphasizing its potential applications in skincare and anti-aging formulations.

Colonic mechanism of serum NAD+ depletion induced by DEHP during pregnancy

Di (2-ethylhexyl) phthalate (DEHP) is a widely used plasticizer in polyvinyl chloride products such as feed piping, packing bag, and medical consumable. Our previous studies have demonstrated that DEHP exposure reduced the concentration of nicotinamide adenine dinucleotide (NAD⁺) in pregnant mice serum, which cuts off the source of NAD⁺ to placenta and results fetal growth restriction. However, the mechanism of serum NAD⁺ depletion by DEHP remains elusive. This study investigated the intestinal mechanism of NAD⁺ shortage-induced by DEHP in pregnant mice. The transcriptome results implicated that the mRNA level of oxidative response genes Cyp1a1, Gsto2, Trpv1 and Trpv3 were upregulated in colon. These changes induced intestinal inflammation. Transmission Electron Microscopy results displayed that DEHP destroyed the tight junctions and cell polarity of colonic epithelial cells. These dysfunctions diminished the expression of NAD⁺ precursor transporters SLC12A8, SLC5A8, SLC7A5, and the NAD⁺ biosynthetic key enzymes NAMPT, NMNAT1-3, and TDO2 in colonic epithelial cells. Analysis of the gut microbiota showed that DEHP led to the dysbiosis of gut microbiota, reducing the relative abundance of Prevotella copri which possesses the VB3 biosynthetic pathway. Therefore, maternal DEHP exposure during pregnancy decreased the transportation of NAD⁺ precursors from enteric cavity to colonic epithelial cells, and inhibited the synthesis of NAD⁺ in colonic epithelial cells. Meanwhile, DEHP reduced the NAD⁺ precursors provided by gut microbiota. Eventually, serum NAD⁺ content was lowered. Taken together, our findings provide a new insight for understanding the intestinal mechanisms by which DEHP affects serum NAD⁺ levels.

Effects of oral administration of equine placental extract supplement on the facial skin of healthy adult women: A randomized, double‐blind, placebo‐controlled study

Introduction

Placenta extract is used as an ingredient in ointments for treating dermatological diseases, skin dryness, and for skin beautification. However, the clinical effects of the equine placenta on humans and the underlying mechanism of action are unclear. This randomized, controlled, double‐blind study aimed to clinically evaluate the effect of oral intake of equine placental extract on human skin quality.

Methods

Healthy women volunteers between the ages of 30 and 59 years (n = 29) were randomly assigned to receive 220 mg of equine placental extract–placebo orally, once daily for 4 weeks. Skin quality parameters such as skin hydration, skin barrier function (transepidermal water loss [TEWL]), and melanin index were assessed at baseline and after 4 weeks of administration.

Results

The melanin index was significantly increased in the placebo group, whereas it remained unchanged in the equine placenta group. The pattern of melanin index change was significantly different due to intake or no intake of equine placenta supplements over 4 weeks. No significant difference was found in skin hydration and TEWL between the two groups at 4 weeks of postadministration. It was shown that the intake of the equine placenta was more effective in protecting the skin condition against the change of ultraviolet (UV) sensitively than the change in temperature and humidity.

Conclusions

Effect of equine placental extract intake was evident on the cheek skin of the equine placenta group where participants were protected from UV‐induced pigmentation. Equine placental extract is useful for decreasing melanin synthesis and melanin content in the human skin and can be used as an effective food supplement to maintain human skin quality.

Effect of Porcine Placenta Extract Supplement on Skin Condition in Healthy Adult Women: A Randomized, Double-Blind Placebo-Controlled Study

Placenta extract has been used as a component of ointments for skin dryness and beautification. However, little is known about the effect of oral intake of placenta extract on skin condition. The current study aimed to clinically explore the effect of oral intake of porcine placenta extract on human skin quality. A randomized controlled double-blind trial was performed on healthy women aged 40–59 years (n = 20), who were randomly assigned to receive either placebo or 200 mg of porcine placenta extract once daily for 4 weeks from 28 January 2019 to 25 February 2019. Skin quality parameters and the Simplified Menopausal Index (SMI) were assessed at baseline and after 4 weeks. After 4 weeks, three parameters of skin quality were significantly improved in the porcine placenta group compared with the placebo group. These results suggest that porcine placenta extract can be used as a health food ingredient to maintain humans’ skin condition in the dry winter season.

Biological interactions between nanomaterials and placental development and function following oral exposure

We summarize the literature involving the deposition of nanomaterials within the placenta following oral exposure and the biological interactions between nanomaterials and placental development and function. The review focuses on the oral exposure of metal and metal oxide engineered nanomaterials (ENMs), carbon-based ENMs, and nanoplastics in animal models, with a minor discussion of intravenous injections. Although the literature suggests that the placenta is an efficient barrier in preventing nanomaterials from reaching the fetus, nanomaterials that accumulate in the placenta may interfere with its development and function. Furthermore, some studies have demonstrated a decrease in placental weight and association with adverse fetal health outcomes following oral exposure to nanomaterials. Since nanomaterials are increasingly used in food, food packaging, and have been discovered in drinking water, the risk for adverse impacts on placental development and functions, with secondary effects on embryo-fetal development, following unintentional maternal ingestion of nanomaterials requires further investigation.

Working group reports: evaluation of the evidence to support practice guidelines for nutritional care of preterm infants-the Pre-B Project

The "Evaluation of the Evidence to Support Practice Guidelines for the Nutritional Care of Preterm Infants: The Pre-B Project" is the first phase in a process to present the current state of knowledge and to support the development of evidence-informed guidance for the nutritional care of preterm and high-risk newborn infants. The future systematic reviews that will ultimately provide the underpinning for guideline development will be conducted by the Academy of Nutrition and Dietetics' Evidence Analysis Library (EAL). To accomplish the objectives of this first phase, the Pre-B Project organizers established 4 working groups (WGs) to address the following themes: 1) nutrient specifications for preterm infants, 2) clinical and practical issues in enteral feeding of preterm infants, 3) gastrointestinal and surgical issues, and 4) current standards of infant feeding. Each WG was asked to 1) develop a series of topics relevant to their respective themes, 2) identify questions for which there is sufficient evidence to support a systematic review process conducted by the EAL, and 3) develop a research agenda to address priority gaps in our understanding of the role of nutrition in health and development of preterm/neonatal intensive care unit infants. This article is a summary of the reports from the 4 Pre-B WGs.

The balancing act - PPAR-γ's roles at the maternal-fetal interface

Peroxisome proliferator-activated receptor-gamma (PPAR-γ) belongs to the nuclear hormone receptor superfamily. Apart from being involved in lipid metabolism, like its other subtypes PPAR α and β, it is implicated to be crucial for successful placentation. While its role in extravillous trophoblast (EVT) differentiation has been studied, the involvement in villous trophoblast (VT) differentiation, fatty-acid metabolism, inflammatory responses, and oxidative pathways during pregnancy deserves more attention. PPAR-γ's potential role in balancing structural development and functional responsibilities at the maternal-fetal interface suggest a more central role for the receptor. The central role of PPAR-γ in pathways related to placental pathologies suggests a potential role of PPAR-γ in placental function. The molecular regulation of PPAR-γ in this context has been widely disregarded. In this review, we discuss the less explored functions of PPAR-γ in the areas of immunological responses and management of oxidative stress in the placenta. We also shed light on the involvement of PPAR-γ in pathologic pregnancies and briefly discuss the current models in the field. The ability to modulate PPAR-γ's activity using already available drugs makes it a tempting therapeutic target. Elucidation of the molecular pathways and specific targets regulated by PPAR-γ will provide more information on the role of PPAR-γ in placentation and related disorders in pregnancy. Furthermore it will close the critical gap in our knowledge about the differential regulation of PPAR-γ in the two trophoblast lineages. This will help to evaluate the usefulness and timing of PPAR-γ modulation in at risk pregnancies to improve placental and endothelial function.

Evidence of steroid hormone activity in the chorioallantoic membrane of a Turtle (Pseudemys nelsoni)

Endocrine properties of extraembryonic membranes have traditionally been viewed as a characteristic of placental amniotes. However, our laboratory recently demonstrated that this ability extends to the extraembryonic membranes of two oviparous amniotes (chicken and alligator) indicating that endocrine extraembryonic membranes are not an innovation of placental amniotes and suggesting that this could be a shared amniote characteristic. In this study, we test our hypothesis that the chorioallantoic membrane (CAM) obtained from non-archosaurian obligate oviparous amniotes such as turtles, have the potential for steroid hormone activity. To investigate synthesis of a major placental hormone, we performed explant culture and found that the turtle CAM synthesizes progesterone in vitro in the presence of a steroid precursor. In addition, to examine whether the CAM has the ability to respond to steroid signaling, we quantified mRNA expression of the progesterone, androgen, and two estrogen receptors. Finally, to determine if steroid receptor mRNA is translated to protein, we performed immunolocalization of the progesterone receptor. Our data demonstrate that the turtle CAM exhibits steroid synthesis and has steroid hormone signaling capabilities. To that end, steroid hormone activity has now been demonstrated in the CAMs of three oviparous species that represent three independent lineages within oviparous Reptilia that have never exhibited viviparity; thus these data support our hypothesis that endocrine activity of extraembryonic membranes is a conserved trait of Amniota.

Dietary fatty acids alter plasma lipids and lipoprotein distributions in dogs during gestation, lactation, and the perinatal period

Alterations of plasma lipids and lipoproteins occur during mammalian pregnancy and reproduction. This study investigated the effects of dietary fatty acids on plasma lipid and lipoprotein alterations during canine gestation, lactation, and the neonatal period. Four diets containing varying amounts of alpha-linolenic acid relative to marine-based (n-3) long-chain fatty acids were studied and fed to dogs from the time of estrus, and throughout pregnancy and lactation. In addition, puppies born to these dams suckled and were weaned using the same diets their mothers had been fed. Plasma cholesterol (total, free, and esterified fractions) and triglycerides were determined at selected time points and lipoprotein fractions were characterized in both mothers and offspring. During gestation, plasma total cholesterol concentrations were depressed early on, then increased in the later stages independently of diet. Both beta- and alpha2-migrating lipoproteins also increased during these times. Lactation was also characterized by lower lipid and lipoprotein amounts compared with the nonpregnant state. In puppies, total plasma and beta-lipoprotein cholesterol were elevated at 4 and 10 d of age. Diet effects included cholesterol, triglyceride, and lipoprotein lowering with increased amounts of marine (n-3) fatty acids in all life stages investigated. The increase in beta-lipoprotein cholesterol in puppies during wk 1 of life is consistent with an earlier report of increased canine apoprotein B,E receptor activities in immature dogs compared with undetectable activities in mature animals in which the HDL fractions become even more predominant in this species.

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.

Expression and role of calcium-ATPase pump and sodium-calcium exchanger in differentiated trophoblasts from human term placenta

Although placental transfer of maternal calcium (Ca(2+)) is a crucial process for fetal development, the biochemical mechanisms are not completely elucidated. Especially, mechanisms of syncytiotrophoblast Ca(2+) extrusion into fetal circulation remain to be established. In the current study we have investigated the characteristics of Ca(2+) efflux in syncytiotrophoblast-like structure originating from the differentiation of cultured trophoblasts isolated from human term placenta. Time-courses of Ca(2+) uptake by differentiated human trophoblasts displayed rapid initial entry (initial velocity (V(i)) of 8.82 +/- 0.86 nmol/mg protein/min) and subsequent establishment of a plateau. Ca(2+) efflux studies with (45)Ca(2+)-loaded cells also showed rapid decline of cell-associated (45)Ca(2+) with a V(i) of efflux (V(ie)) of 8.90 +/- 0.96 nmol/mg protein/min. Expression of membrane systems responsible for intracellular Ca(2+) extrusion from differentiated human trophoblast were investigated by RT-PCR. Messenger RNAs of four known isoforms of PMCA (PMCA 1-4) were detected. Messenger RNAs of two cloned human NCX isoforms (NCX1 and NCX3) were also revealed. More specifically, both splice variants NCX1.3 and NCX1.4 were amplified by PCR with total RNA of differentiated human trophoblast cells. Ca(2+) flux studies in Na-free incubation medium indicated that NCX played a minimal role in the cell Ca(2+) fluxes. However, erythrosine B (inhibitor of PMCA) time- and dose-dependently increased cell associated (45)Ca(2+) suggesting a principal role of plasma membrane Ca(2+)-ATPase (PMCA) in the intracellular Ca(2+) extrusion of syncytiotrophoblast-like structure originating from the differentiation of cultured trophoblast cells isolated from human term placenta.

Expression of calcium channels along the differentiation of cultured trophoblast cells from human term placenta

Placental transfer of maternal calcium (Ca2+) is carried out in vivo by the syncytiotrophoblast layer. Although this process is crucial for fetal development, it remains poorly understood. Cytotrophoblasts isolated from human term placenta undergo spontaneous syncytiotrophoblast-like morphological and biochemical differentiation in vitro and are thought to reflect in vivo syncytiotrophoblast. In the present study, we characterized the Ca2+ uptake potential and the expression of several Ca2+ channels by human trophoblasts during differentiation in vitro for up to 6 days. Secretion of hCG (specific differentiation marker) and uptake of Ca2+ by trophoblasts increased gradually as a function of days in culture. Both hCG secretion and Ca2+ uptake were maximal on Day 4 and declined on Days 5-6. Expression of the Ca2+ transporter proteins CaT1 and CaT2 was revealed by reverse transcription-polymerase chain reaction in cytotrophoblasts freshly isolated from human term placenta. In addition, messengers for two L-type Ca2+ channel isoforms (alpha(1C) and alpha(1D)) were also detected. Levels of CaT1, CaT2, and L-type Ca2+ channel mRNA increased gradually during culture, reaching a maximum between Days 2 and 3. In contrast to CaT1 and CaT2 expression that declined thereafter to levels observed on Day 1, L-type channel expression decreased by 50% but remained above the expression level of Day 1. Our results indicate that the pattern of CaT1 and CaT2 expression correlates with the Ca2+ uptake potential along the differentiation of cultured human trophoblasts isolated from term placenta. This correlation provides circumstantial evidence for a role of this family of channels in basal Ca2+ uptake by the syncytiotrophoblast.

Calcium uptake and calcium transporter expression by trophoblast cells from human term placenta

Placental transfer of maternal calcium (Ca(2+)) is a crucial step for fetal development although the biochemical mechanisms responsible for this process are largely unknown. This process is carried out in vivo by the placental syncytiotrophoblast layer. The aim of this study was to define the membrane gates responsible for the syncytiotrophoblast Ca(2+) entry, the first step in transplacental transfer. We have investigated the basal Ca(2+) uptake by primary culture of human term placenta syncytiotrophoblast. Kinetic studies revealed an active extracellular Ca(2+) uptake by cultured human syncytiotrophoblast. We demonstrated by Northern blot the presence of transcript for calcium transporter type 1 (CaT1) in cultured human syncytiotrophoblast and CaT1 expression was further confirmed by reverse transcription polymerase chain reaction (RT-PCR). In addition, the expression of calcium transporter type 2 (CaT2) was revealed by RT-PCR in cultured human syncytiotrophoblast. It has been reported that the activity of this family of Ca(2+) channels is voltage-independent, and is not sensitive to L-type Ca(2+) channels agonist and antagonist. Interestingly, modulation of membrane potential by extracellular high potassium concentration and valinomycin had no effect on the basal Ca(2+) uptake of human syncytiotrophoblast. Moreover, the addition of L-type Ca(2+) channel modulators (Bay K 8644 and nitrendipine) to the incubation medium had also no effect on the basal Ca(2+) uptake, suggesting that the process is mainly voltage-independent and does not involved L-type Ca(2+) channels. On the other hand, we observed that two known blockers of CaT-mediated Ca(2+) transport, namely extracellular magnesium (Mg(2+)) and ruthenium red, dose-dependently inhibited Ca(2+) uptake by cultured human syncytiotrophoblast. Therefore, our results suggest that basal Ca(2+) uptake of human syncytiotrophoblast may be assured by CaT1 and CaT2.

Characteristics of calcium uptake by BeWo cells, a human trophoblast cell line

Placental transfer of maternal calcium (Ca(2+)) is a crucial process for fetal development although the biochemical mechanisms responsible for this transfer are largely unknown. We have investigated the characteristics of Ca(2+)uptake by the human placental trophoblast cell line BeWo. The kinetics studies revealed an active extracellular Ca(2+)uptake by BeWo cells, which was rapid in the first 2 min (initial velocity (V(i)) of 4.17+/-0.25 nmol/mg/min), and showed a subsequent plateau. Uptake experiments performed at V(i)with increasing concentrations of Ca(2+)resulted in a typical saturation curve (K(m)of 0.54+/-0.07 m m and V(max)of 7.07+/-0.28 nmol/mg protein/min). Lowering the pH of the incubation medium from 7.4 to 5.5 led to Ca(2+)uptake inhibition of 40-50 per cent. The presence of voltage-sensitive (l -type) Ca(2+)channels in BeWo cells was demonstrated by Western blot. Therefore, the implication of such channels in basal Ca(2+)uptake of BeWo cells was investigated. Cell depolarization with extracellular high potassium concentration (40 m m), and hyperpolarization with extracellular high chloride concentration (60 m m) or with valinomycin (10 microm) did not influence the basal Ca(2+)uptake of BeWo cells. The L-type Ca(2+)channel modulators (Bay K 8644 and Nitrendipine) had no effect on the Ca(2+)uptake. An antagonist of receptor-mediated, store-operated and voltage-gated Ca(2+)channels (SKF-96365) also did not modulate the Ca(2+)uptake of BeWo cells. Therefore, our results indicate that the basal Ca(2+)uptake of BeWo cells is inhibited by lowering pH of the incubation medium, is voltage independent, and is not influenced by l -type Ca(2+)channel and capacitative Ca(2+)conductance modulators.

Combined effect of high-fat diet and copper deficiency during gestation on fetal copper status in the rat

We have previously shown that a low-copper (Cu) diet produced alterations in placental Cu transport and fetal Cu stores. Because Cu deficiency has been associated with lipid deposition in rat dam liver, we hypothesized that a high fat intake, a prevalent dietary habit in many populations, may worsen fetal Cu status and its closely linked iron (Fe) deposits. Pregnant rats were fed one of four diets during the second half of gestation: NFNCu: normal fat (7%), normal Cu (6 mg/kg); HFNCu: high fat (21%), normal Cu; NFLCu: normal fat, low Cu (0.6 mg/kg), and HFLCu: high fat, low Cu. One day before delivery, dams were anesthetized, and maternal as well as fetal plasma and tissues were obtained. Maternal, fetal, and placental weights were indistinguishable regardless of the group. Dam plasma Cu and placental Cu were lower in both LCu groups than in the NFNCu or the HFNCu groups. However, fetal plasma Cu was similar in all treatment groups. Dam and fetal liver Cu stores were reduced in the LCu groups compared to the NCu groups. This resulted in lower fetal/maternal liver Cu ratios in the NFLCu (1.79+/-0.14, p < 0.05) and HFLCu (1.59+/-0.21, p < 0.05) as compared to the NFNCu (4.12+/-0.44) and the HFNCu (4.15+/-0.27). Dam liver Fe was higher in the NFNCu than in HFNCu group (1.10+/-0.8 vs. 0.89+/-0.06 micromol/g, p < 0.05); fetal liver Fe from HFNCu and NFLCu dams was lower than that from NFNCu fetuses (NFNCu: 2.42+/-0.14; HFNCu: 1.92+/-0.15, p < 0.05; NFLCu: 1.81+/-0.10, p < 0.01). Fetuses of the HFLCu group had a lower heart Fe than the NFNCu group (0.56+/-0.03 vs. 44.0+/-3.0 microg/g, p < 0.01). These data indicate that a maternal high-fat diet can potentially aggravate the effects of Cu deficiency by further altering fetal Cu and Fe tissue stores.

Serum levels of unbound free fatty acids. II: The effect of intralipid administration in premature infants

BACKGROUND

Fatty acids (FFA) are key nutrients in maintaining physiologic homeostasis and in the form of Intralipid administration, they are important sources of nutrition in the premature newborn infant. Complexed with albumin, fatty acids have a small but important fraction that remains unbound in the aqueous phase.

OBJECTIVE

The goal of this study was to examine the levels of serum levels of unbound free fatty acids (FFAu) in premature newborns following Intralipid administration.

METHOD

A fluorescent probe acrylodated intestinal fatty acid binding protein (ADIFAB) was used to measure (FFAu) before Intralipid and during increasing rates of infusion.

RESULTS

There were significant differences between (FFAu) values obtained before Intralipid and levels after the infusion of 1.0, 2.0, and 3.0 g/kg/day (p < 0.05). Regression analysis of Intralipid dose and FFAu yielded an r = 0.438 and the following relationship: [FFAu] = 26.39 + 3.60 * IL (g/kg/day).

CONCLUSIONS

Intralipid administration results in significant elevation of FFAu in the very low birth weight infant.

Plasma membrane fatty acid-binding protein (FABPpm) of the sheep placenta

Fatty acid-binding protein (FABPpm) has been identified and characterised from sheep placental membranes. Binding of [14C]oleate to placental membranes was found to be time- and temperature-dependent. Addition of a 20-fold excess unlabelled oleic, palmitic, or linoleic acid reduced the binding of [14C]oleate to the membranes to around 50% of total binding, whereas D-alpha-tocopherol at similar concentrations did not affect [14C]oleate binding. This indicates that the binding sites are specific to fatty acids. Specific binding of [14C]oleate was reduced by heat denaturation or trypsin digestion of the membranes, suggesting that the fatty acid-binding sites are protein in nature. FABPpm was then solubilised from sheep placental membranes, and subsequently purified to electrophoretic homogeneity using an oleate-agarose affinity column. The purified FABPpm had an apparent molecular mass of 40 kDa, as determined by SDS-PAGE and by gel permeation chromatography. The [14C]oleate-binding activity of the purified protein was also confirmed by PAGE followed by autoradioblotting. The specific binding for oleate was around 1.5 nmol per mg of membrane protein. Our data indicate the presence of FABPpm in sheep placental membranes.

Developmental expression of Glut1 glucose transporter and c-fos genes in human placental cells

Glut1, the brain/erythrocyte glucose transporter is one major isoform of the human placenta and displays an age-specific pattern of expression with mRNA levels five-fold higher in first trimester than in term placenta. By contrast, the mRNA level of the insulin-regulatable glucose transporter Glut4 remains at the limit of detection throughout pregnancy indicating a very low expression of this isoform in the placenta. The nuclear proto-oncogenes c-fos and c-myc were also detectable in the human placenta, but c-fos only exhibited an age-specific pattern of expression with levels higher in third trimester than in term placenta. Primary cultures of human trophoblast cells from term placenta were used to further study the expression and regulation of Glut1 and c-fos genes. Fetal calf serum rapidly and transiently (15 to 60 min) stimulated c-fos and Glut1 gene expression suggesting that both genes share similar growth factor-controlled pathways. Glucose inhibited Glut1, but not c-fos expression. An eight-fold decrease in Glut1 mRNA was observed when glucose concentration in the medium was increased from 0 to 25 mM, whereas c-fos mRNA levels remained very low. These results suggest that in the human placenta, the expression of Glut1 is specifically regulated by glucose concentration. These data demonstrate that (1) Glut1 and c-fos mRNA transcripts are expressed in the human placenta exhibiting an age-specific pattern of expression, (2) In cultured trophoblast cells, both genes are stimulatable by fetal calf serum and in contrast to c-fos, Glut1 is negatively regulated by glucose. This differential regulation of Glut1 and c-fos genes could be relevant to specific metabolic and mitogenic pathways implicated in placental growth and differentiation.

Element variations in pregnant and nonpregnant female rats orally intoxicated by aluminum lactate

Pregnant or nonpregnant female rats were orally intoxicated by aluminum lactate (400 mg Al/kg/d) from d 0-19 of gestation to determine the treatment's influence on element variations in the females and their fetuses. The aluminum levels of plasma, liver, spleen, and kidneys were significantly higher in treated pregnant rats than non-pregnant female rats. Differences of P, Ca, Cu, Zn, or Mg levels were observed among the four groups of female rats in the tissues and plasma. The aluminum content of the 20-d-old fetuses did not significantly differ between the treated and control groups. On the contrary, calcium and magnesium levels in the whole fetuses from treated or nontreated dams are significantly different.

Balance of amino acids in the pregnant human uterus at term

The nutritive and metabolic state of the human uterus at term is evaluated by measuring the uptake and release of amino acids. The subjects are ten healthy women with normal pregnancy undergoing elective caesarean section at term, before onset of labour. Free amino acids in arterial (radial artery) and venous (plexus of the uterine and ovarian veins) blood are determined and arteriovenous (AV) differences in each amino acid across the uterus are calculated. Generally the AV differences are negative, i.e. uterus at term releases amino acids in most cases. The human pregnant uterus at term is characterized by a release of amino acids rather than uptake. This indicates that they are in excess and are not needed in anabolic processes or as a fuel, even when the uterine tissue at term is supposed to be preparing for its grand performance, i.e. the delivery.

Protein turnover in rat placenta: effects of maternal fasting and maternal protein restriction

Biochemical composition and variables of protein turnover were determined in rat placenta at 21 days gestation in control animals and in animals subjected to 72-h fasting and protein/calorie restriction (6 per cent protein) throughout gestation. Placental protein synthesis was determined following the injection of 'massive' amounts of 14C-phenylalanine intravenously to the pregnant rat. Protein content was reduced in placentas from rats that were fasted for 72 h and in those who were protein restricted throughout pregnancy. Placental RNA content was significantly reduced only in the protein-restricted animals. Fractional rates of protein synthesis were reduced in placentas from the protein-restricted animals (Ks = 17.9 +/- 0.8 per cent per day in controls versus 11.7 +/- 0.9 in protein restricted, P = 0.002), but not in fasted animals. Fractional protein breakdown was markedly enhanced in placentas following maternal fasting (Kd = 9.9 per cent per day in controls versus 26.0 per cent in fasted), but not affected by protein deprivation. These results mimic those previously reported for other fetal tissues under these experimental conditions.

Na(+)-dependent amino acid uptake by human placental microvillous membrane vesicles: importance of storage conditions and preservation of cytoskeletal elements

Human placental microvillous membrane vesicles (MMV) were purified by precipitation of non-microvillous membrane with MgCl2. Two aspects of MMV preparation were found to be important to the interpretation of amino acid transport studies: (1) storage conditions, and (2) preservation of cytoskeletal elements. In non-frozen MMV, MeAIB uptake was stimulated by an inward Na+ gradient and showed 'overshoot'. The initial Na(+)-dependent uptake rate was concentration-dependent with a Vmax of 640 +/- 80 pmol/mg/30 sec and a Km of 0.44 +/- 0.77 mM. Na(+)-stimulated cysteine uptake (65 +/- 23 pmol/mg/30 sec), previously thought to be very low or absent in the human placenta, was comparable to MeAIB, although there was no 'overshoot'. Cysteine uptake was partially stimulated by Li+. In general, freezing and storage at either -80 degrees C or -196 degrees C markedly reduced Na(+)-dependent uptake of several amino acids, compared to vesicles stored at 4 degrees C. The greatest reduction was seen with storage at -80 degrees C, especially with cysteine. There was no effect of storage temperature on Na(+)-independent amino acid uptake. For frozen vesicles, there was no difference in uptake for 12 versus 60 h storage. Removal of cytoskeletal proteins with the chaotropic agent, KSCN, resulted in greater enrichment of MMV marker proteins, but the preparation lost the capacity for active MeAIB uptake. These data, especially with regard to storage conditions, highlight the importance of precise definition of preparation and storage conditions when interpreting results of amino acid uptake by human placental MMV.

[Supply, metabolism and biological effects of trans-isomeric fatty acids in infants]

Consumption of trans-fatty acids increased markedly during this century due to the widespread use of partially hydrogenated fats. A sensitive analytical method was developed which enables the precise determination of 7 trans-isomers in small sample volumes. With this method we documented the materno-fetal transfer of trans-fatty acids across the human placenta. The content in human milk depends on maternal diet and is lower in Germany than in the Sudan. The distribution in fore- and hind-milk, in milk fat fractions and within the triglyceride molecule was determined. The content of trans-fatty acids is lower in commercial and home-made infant formulae than in human milk, although there is a certain batch to batch variation in formulae. Infants absorb dietary trans-isomers and incorporate them into endogenous lipids, subcutaneous tissue and cell membranes. Trans-fatty acids in plasma lipids are significantly higher in infants fed human milk than in those fed formulae. African children have a lower exposure than Germans. The relative contribution of trans-octadecenoic acid is lower in plasma sterol esters than in triglycerides and phospholipids, pointing to a negative selectivity of plasmatic cholesterol esterification with this fatty acid. Thus, a high supply of trans-octadecenoic acid might have negative effects on the cholesterol levels. In premature infants we found an inverse correlation between trans-fatty acid exposure and birthweight, thus interference with intrauterine growth appears possible. A possible causative factor could be impaired biosynthesis of long-chain polyunsaturated fatty acids by trans-isomers, for which we found strong indications. The results of our investigations the question whether the consumption of trans-fatty acids in pregnant and lactating women and in infants is nutritionally safe.

Ethanol consumption during pregnancy in mice: effects on hormone concentrations

Hormonal and metabolic responses to ethanol consumption were studied in pregnant Swiss Webster mice and their fetuses. On day 10 of pregnancy, mice were assigned to one of three liquid diet groups: 36% ethanol-derived calories fed ad libitum (ETOH); control liquid diet fed ad libitum (control); control liquid diet administered in the same amount as that consumed by the ETOH group on the same day of pregnancy [pair-fed controls (PF)]. Dams were killed on days 14-18 of pregnancy, and fetuses were collected on days 16-18. Serum mouse placental lactogen-II (mPL-II), prolactin (mPRL), growth hormone (mGH), insulin, and glucose concentrations were determined for each group. Ethanol consumption resulted in a significant reduction in fetal weight on day 18 of pregnancy. The maternal serum mPRL concentration was reduced in ETOH mice on days 16 and 17 of pregnancy when compared with control mice, but when compared with PF mice, it was significantly reduced only on day 16. Maternal and fetal serum insulin concentrations were reduced in ETOH mice when compared with control mice, but it is unclear whether this was a specific effect of ethanol consumption or due to reduced food intake. Maternal serum glucose concentrations were reduced in the ETOH mice but not as severely as in the PF mice. Ethanol consumption had no effect on maternal or fetal serum mPL-II and mGH concentrations. These data confirm that ethanol consumption during pregnancy results in fetal growth retardation, but they do not indicate any major effects of ethanol on mPL-II, mPRL, mGH, and insulin concentrations in either the mother or fetus.

Effect of continuous feeding on maternal protein metabolism and fetal growth in the rat

Accelerated maternal catabolism ensures adequate fetal growth in the postabsorptive pregnant mammal during late gestation. However, the relative importance of maternal stores and diet in supplying nutrient requirements to the fetus is unknown. We have measured rates of protein synthesis and breakdown in maternal and fetal tissues during continuous intravenous feeding on days 17 and 20 in the rat, using leucine tracer infusions. Nutrient solutions supplying 180 and 250 kcal.kg-1.day-1 were tested. Changes in fetal size were measured in these rats and in rats maintained on ad libitum chow feeding. In comparison to previous results in the postabsorptive rat, leucine flux from endogenous sources into plasma was significantly suppressed, with only 12-20% of circulating leucine derived from maternal tissues. Muscle protein catabolism (previously described on day 20 of gestation) was abolished with continuous feeding. Fetal growth rate averaged 46%/day on day 17 of gestation in all groups but was reduced to 12%/day on day 20 in the rats intravenously fed 180 kcal.kg-1.day-1 and 22%/day in the rats fed 250 kcal.kg-1.day-1. Fetal growth on day 20 in the rats fed rat chow ad libitum was unaffected. We conclude that by decreasing the maternal contribution to circulating nutrients, continuous intravenous feeding may adversely affect fetal growth in late pregnancy. The findings in the current study underline the physiological importance of maternal-fetal nutrient exchange.

Mouse placental 57-kDa calcium-binding protein: II. Localization of mRNA in mouse and human placentae by in situ cDNA hybridization

Using a cloned cDNA to the mouse placental calcium-binding protein (MCaBP) [Tuan and Kirwin, preceding paper], mRNA transcripts of the MCaBP have been localized in the mouse placenta by in situ cDNA-RNA hybridization. The procedure involved the use of a nonradioactive, biotinylated cDNA probe. Paraffin sections of the mouse chorioallantoic placenta were processed for in situ hybridization using a procedure modified from that of Lo [8]. The results demonstrated that MCaBP mRNA is localized specifically to the fetal trophoblast of the mouse placenta, and is expressed in a development-dependent manner. The MCaBP cDNA also hybridized strongly in situ to sections of human term placenta, giving rise to signals localized specifically to the syncytiotrophoblastic layer of the chorionic villi.

Regulation of fetal lung disaturated phosphatidylcholine synthesis by de novo palmitate supply

Lung surfactant disaturated phosphatidylcholine (PC) is highly dependent on the supply of palmitate as a source of fatty acid. The purpose of this study was to investigate the importance of de novo fatty acid synthesis in the regulation of disaturated PC production during late prenatal lung development. Choline incorporation into disaturated PC and the rate of de novo fatty acid synthesis was determined by the relative incorporation of [14C]choline and 3H2O, respectively, in 20-day-old fetal rat lung explants and in 18-day-old explants which were cultured 2 days. Addition of exogenous palmitate (0.15 mM) increased (26%) choline incorporation into disaturated PC but did not inhibit de novo fatty acid synthesis, as classically seen in other lipogenic tissue. Even in the presence of exogenous palmitate, de novo synthesis accounted for 87% of the acyl groups for disaturated PC. Inhibition of fatty acid synthesis by agaric acid or levo-hydroxycitrate decreased the rate of choline incorporation into disaturated PC. When explants were subjected to both exogenous palmitate and 60% inhibition of de novo synthesis, disaturated PC synthesis was below control values and 75% of disaturated PC acyl moieties were still provided by de novo synthesis. These data show that surfactant disaturated PC synthesis is highly dependent on the supply of palmitate from de novo fatty acid synthesis.

Control of placental glucose transfer

There is little evidence to suggest that the membrane transfer mechanism of the placenta for glucose becomes saturated until maternal blood glucose concentrations are quite high. Also, recent evidence suggests that the membrane transport system for glucose in the placenta is not stimulated by maternal or fetal insulin. Furthermore, there is no solid evidence that hormonal or non-hormonal factors function in vivo to limit membrane transport of glucose in the placenta. Therefore, the limited data which are available suggest that there are no specific mechanisms which acutely regulate placental membrane transport of glucose, and that this membrane transport mechanism operates to maximize maternal-to-fetal glucose transfer. The rate of maternal-to-fetal glucose transfer is a function of the transplacental concentration gradient. This gradient appears to be under the control of fetal insulin and placental lactogen. The available data suggest that both hormones act to increase this concentration gradient: insulin by decreasing fetal blood glucose, and placental lactogen by both decreasing fetal and increasing maternal blood glucose concentrations. Furthermore, high rates of glucose uptake by fetal erythrocytes tend to promote maintenance of this concentration gradient. Therefore, these influences of the maternal-fetal concentration gradient promote transplacental glucose flux to the fetus. As illustrated by the fetal complications associated with maternal hyperglycaemia, the cellular and organismic physiology of the fetus and placenta appears to maximize, rather than optimize, glucose availability to the fetus. It may be, however, that during normal pregnancy, maximal availability is optimal for fetal development.

Identification of high affinity folate binding proteins in human erythrocyte membranes

Mature human erythrocyte membranes contained specific, high affinity (Kd 3.3 X 10(-11) M) folate binding moieties. Folate binding was pH, time- and temperature-dependent, saturable, and was much greater for pteroylmonoglutamate and 5-methyltetrahydrofolate than 5-formyltetrahydrofolate and amethopterin. On detergent solubilization of membranes, two peaks of specific folate binding with Mr greater than or equal to 200,000 and 160,000 were identified on Sephacryl S-200 gel filtration chromatography in Triton X-100, and this corresponded to two similar peaks of immunoprecipitated material when solubilized iodinated membranes were probed with anti-human placental folate receptor antiserum. Age-dependent separation of erythrocytes by Stractan density gradients revealed a sevenfold greater folate binding capacity in membranes purified from younger compared with aged erythrocytes. Since this difference was not reflected in proportionately higher immunoreactive folate binding protein, (as determined by a specific radioimmunoassay for these proteins), or differences in affinity in younger than aged cells, these findings indicate that erythrocyte folate binding proteins become progressively nonfunctional at the onset of red cell aging.

Effects of fasting on serum lactogenic hormone concentrations during mid- and late pregnancy in mice

Hormonal and metabolic responses to fasting were studied in pregnant Swiss Webster mice. Food was removed from pregnant mice 12, 24, 36, or 48 h before death on day 12 or 15 of pregnancy. Serum mouse placental lactogen-II (mPL-II), mouse growth hormone (mGH), mouse prolactin (mPRL), free fatty acids (FFA), and glucose concentrations were determined for each group. In comparing fasted animals with fed controls, there was a significant increase in the serum mPL-II concentration after 24 and 48 h of fasting on day 12 and after 12, 36, and 48 h of fasting on day 15. Fasting significantly decreased the glucose and increased the FFA concentration of the serum at all fasting periods. Fasting had no effect on serum mPRL or mGH concentrations. In the second part of this study, pregnant mice were fasted for 24 h and then refed for an additional 24 h before being killed on day 12 of pregnancy. The changes in serum mPL-II, glucose, and FFA concentrations that occurred after a 24-h fast on day 12 of pregnancy were completely reversed by refeeding the animals for 24 h. Results from both studies indicate the involvement of mPL-II in the maternal response to fasting in pregnant mice.

Calcium-activated ATPase of the human placenta: identification, characterization, and functional involvement in calcium transport

A specific, membrane-bound, Ca2+-activated and Mg2+-dependent adenosine triphosphatase (ATPase) activity is present in the human term placenta. The enzyme activity is fractionated electrophoretically into two distinct forms which correspond to molecular weights of 120,000 and 145,000. Cytohistochemistry localized the Ca2+-ATPase to the chorionic villi of the placental labyrinth, and specific staining was primarily associated with the syncytio- and cytotrophoblast layers as well as the perivascular cells. The enzyme activity is inhibited by phenothiazin and erythrosin B which also significantly inhibit active calcium in vitro by placental microsomal membrane vesicles.

Fatty acid synthesis in the fetal lung: relationship to surfactant lipids

The aims of this study were to investigate the control of fatty acid synthesis and its relationship to surfactant production in the fetal lung during alteration of hormonal and substrate conditions. Lung explants from 18 day fetuses (term = 22 days) which were cultured 2 days in the presence of 10 mM lactate showed parallel acceleration of de novo fatty acid synthesis (3H2O incorporation) and [14C]choline incorporation into disaturated phosphatidylcholine (DSPC) compared to culture of explants in glucose. Both the cultured and fresh explants were resistant to the classical short term (4 h) cAMP inhibition of fatty acid synthesis with 3 mM dibutyryl cAMP or 0.5 mM aminophylline. In the cultured explants short term cAMP elevation increased DSPC production, and long term (2 day) cAMP elevation caused a further increase in DSPC synthesis and also stimulated fatty acid synthesis. In cultured explants from 17 day fetuses, dexamethasone (0.1 microM) caused a synergistic increase with aminophylline in both fatty acid synthesis and DSPC production whereas, in explants from 18 day fetuses, dexamethasone inhibited both processes and reduced the level of stimulation of DSPC and fatty acid synthesis seen with aminophylline alone. Dexamethasone also reduced the stimulation of both DSPC and fatty acid synthesis produced in the culture of 18 day explants with bacitracin (0.5 mg/ml), whereas the combination of bacitracin and aminophylline resulted in a synergistic increase in DSPC production. Culture with glucagon (0.1 microM) also stimulated DSPC synthesis but at physiological levels insulin had no effect on either DSPC or fatty acid synthesis. These data show that lung fatty acid synthesis exhibits unique features of fatty acid synthesis regulation compared to other lipogenic tissues and also suggest a link between de novo fatty acid synthesis and surfactant production during the critical period of accelerated lung maturation.

Transport of folates at maternal and fetal sides of the placenta: lack of inhibition by methotrexate

Folate (pteroylglutamate) and methotrexate rapid (seconds) uptake by the trophoblast was investigated from either the maternal or fetal circulations of the isolated dually-perfused guinea-pig placenta. Tissue uptake was measured by using a single-circulation paired-tracer (3H-test and 14C-extracellular marker) technique. [3H]Folate uptakes were 80 and 52% (mean) in perfusates without unlabelled folate, on maternal and fetal sides, respectively. There was negligible 3H-tracer backflux into the circulation up to 6 min probably due to metabolic sequestration. [3H]Methotrexate uptakes were about 85 and 22% on maternal and fetal sides, respectively; however these uptakes were followed by rapid and complete backflux of the label. Specific transplacental transfer of [3H]folate or [3H]methotrexate in either direction was not detectable within 5-6 min. At the brush-border side (maternal) uptake of [3H]folate was highly inhibited by 100 nM unlabelled folate or its reduced form, methyltetrahydrofolate (the main form in plasma); however, equimolar methotrexate (an antifolate chemotherapeutic agent) failed to produce any inhibition of folate uptake. Our findings demonstrate that on both sides of the placenta a high-affinity transport system exists for trophoblast uptake of folate compounds. For methotrexate, either a separate transport system may exist or methotrexate may have a very low affinity for the folate system. These results are distinct from the findings reported in mouse L1210 leukemia cells.