Brain-derived neurotrophic factor promotes implantation and subsequent placental development by stimulating trophoblast cell growth and survival

Brain-derived neurotrophic factor improves proliferation of endometrial epithelial cells by inhibition of endoplasmic reticulum stress during early pregnancy

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family binds to two transmembrane receptors; neurotrophic receptor tyrosine kinase 2 (NTRK2) with high affinity and p75 with low affinity. Although BDNF-NTRK2 signaling in the central nervous system is known, signaling in the female reproductive system is unknown. Therefore, we determined effects of BDNF on porcine endometrial luminal epithelial (pLE) cells isolated from Day 12 of pregnancy, as well as expression of BDNF and NTRK2 in endometria of cyclic and pregnant pigs. BDNF-NTRK2 genes were expressed in uterine glandular (GE) and luminal (LE) epithelia during early pregnancy. In addition, their expression in uterine GE and LE decreased with increasing parity of sows. Recombinant BDNF increased proliferation in pLE cells in a dose-dependent, as well as expression of PCNA and Cyclin D1 in nuclei of pLE cells. BDNF also activated phosphorylation of AKT, P70S6K, S6, ERK1/2, JNK, P38 proteins in pLE cells. In addition, cell death resulting from tunicamycin-induced ER stress was prevented when pLE cells were treated with the combination of tunicamycin and BDNF which also decreased cells in the Sub-G₁ phase of the cell cycle. Furthermore, tunicamycin-induced unfolded protein response genes were mostly down-regulated to the basal levels as compared to non-treated pLE cells. Our finding suggests that BDNF acts via NTRK2 to induce development of pLE cells for maintenance of implantation and pregnancy by activating cell signaling via the PI3K and MAPK pathways and by inhibiting ER stress.

WITHDRAWN: Neurotrophins and specific receptors in the oviduct tracts of Japanese quail (Coturnix coturnix japonica)

The Publisher regrets that this article is an accidental duplication of an article that has already been published in Ann. Anat., 210 (2017) 112 – 120>, http://dx.doi.org/10.1016/j.aanat.2016.04.034. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Serum brain-derived neurotrophic factor (BDNF) across pregnancy and postpartum: Associations with race, depressive symptoms, and low birth weight

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is implicated as a causal factor in major depression and is critical to placental development during pregnancy. Longitudinal data on BDNF across the perinatal period are lacking. These data are of interest given the potential implications for maternal mood and fetal growth, particularly among Black women who show ∼2-fold greater risk for delivering low birth weight infants.

METHODS

Serum BDNF, serum cortisol, and depressive symptoms (per CES-D) were assessed during each trimester and 4-11 weeks postpartum among 139 women (77 Black, 62 White). Low birth weight (<2500g) was determined via medical record.

RESULTS

Serum BDNF declined considerably from 1st through 3rd trimesters (ps≤0.008) and subsequently increased at postpartum (p<0.001). Black women exhibited significantly higher serum BDNF during the 1st trimester, 2nd trimester, and postpartum (ps≤0.032) as well as lower serum cortisol during the 2nd and 3rd trimester (ps≤0.01). Higher serum cortisol was concurrently associated with lower serum BDNF in the 2nd trimester only (p<0.05). Controlling for race, serum BDNF at both the 2nd and 3rd trimester was negatively associated with 3rd trimester depressive symptoms (ps≤0.02). In addition, women delivering low versus healthy weight infants showed significantly lower serum BDNF in the 3rd trimester (p=0.004). Women delivering low versus healthy weight infants did not differ in depressive symptoms at any time point during pregnancy (ps≥0.34).

CONCLUSIONS

Serum BDNF declines considerably across pregnancy in Black and White women, with overall higher levels in Blacks. Lower serum BDNF in late pregnancy corresponds with higher depressive symptoms and risk for low birth weight in Black and White women. However, the predictive value of serum BDNF in pregnancy is specific to within-race comparisons. Potential links between racial differences in serum BDNF and differential pregnancy-related cortisol adaptation require further investigation.

Maternal obesity alters brain derived neurotrophic factor (BDNF) signaling in the placenta in a sexually dimorphic manner

INTRODUCTION

Obesity is a major clinical problem in obstetrics being associated with adverse pregnancy outcomes and fetal programming. Brain derived neurotrophic factor (BDNF), a validated miR-210 target, is necessary for placental development, fetal growth, glucose metabolism, and energy homeostasis. Plasma BDNF levels are reduced in obese individuals; however, placental BDNF has yet to be studied in the context of maternal obesity. In this study, we investigated the effect of maternal obesity and sexual dimorphism on placental BDNF signaling.

METHODS

BDNF signaling was measured in placentas from lean (pre-pregnancy BMI < 25) and obese (pre-pregnancy BMI>30) women at term without medical complications that delivered via cesarean section without labor. MiRNA-210, BDNF mRNA, proBDNF, and mature BDNF were measured by RT - PCR, ELISA, and Western blot. Downstream signaling via TRKB (BDNF receptor) was measured using Western blot.

RESULTS

Maternal obesity was associated with increased miRNA-210 and decreased BDNF mRNA in placentas from female fetuses, and decreased proBDNF in placentas from male fetuses. We also identified decreased mature BDNF in placentas from male fetuses when compared to female fetuses. Mir-210 expression was negatively correlated with mature BDNF protein. TRKB phosphorylated at tyrosine 817, not tyrosine 515, was increased in placentas from obese women. Maternal obesity was associated with increased phosphorylation of MAPK p38 in placentas from male fetuses, but not phosphorylation of ERK p42/44.

DISCUSSION

BDNF regulation is complex and highly regulated. Pre-pregnancy/early maternal obesity adversely affects BDNF/TRKB signaling in the placenta in a sexually dimorphic manner. These data collectively suggest that induction of placental TRKB signaling could ameliorate the placental OB phenotype, thus improving perinatal outcome.

Niveles séricos del factor neurotrófico derivado del cerebro durante la gestación normal y la preeclampsia

<p>Introducción. La preeclampsia (PE) es una de las principales causas de mortalidad materna y perinatal en el mundo, aparece en la segunda mitad de la gestación y actualmente no hay marcadores que la detecten en forma temprana. Dadas las propiedades angiogénicas del factor neurotrófico derivado del cerebro (BDNF) y la disfunción endotelial de los vasos sanguíneos presente en la PE, se ha propuesto una posible asociación entre el BDNF y PE. Objetivo. Determinar si existe asociación entre niveles séricos de BDNF durante el embarazo y la preeclampsia. Materiales y métodos. Estudio de cohorte prospectivo longitudinal. Se seleccionaron 13 pacientes quienes desarrollaron PE y 31 gestantes de curso normal. Se midieron variables antropométricas y niveles de BDNF, glicemia, insulina y perfil lipídico en la gestación temprana, media y tardía. Se practicó un modelo de regresión logística para verificar si los niveles de BDNF, en conjunto con otras variables, pueden explicar el desarrollo de PE. Resultados. Los niveles de BDNF no variaron significativamente entre el grupo de gestantes que desarrollaron preeclampsia y las que no: en gestación temprana 25.3 y 23.3ng/ml, en gestación media 28 y 24.7ng/ml y en gestación tardía 25.4 y 27.4ng/ml, respectivamente. Se hallaron diferencias entre los dos grupos en el peso, la insulina y la evaluación del modelo homeostático (HOMA). Se encontró asociación entre niveles de BDNF y peso e IMC y glucemia en las gestantes que no desarrollaron PE. Se practicó un modelo de regresión logística en el que la PE se explicó mejor con variables como IMC, PAS y HOMA, pero no con BDNF. Conclusiones. El BDNF puede participar en la regulación del peso corporal y el metabolismo de la glucosa en mujeres gestantes, pero el nivel de BDNF, solo o en conjunto con otras variables, no puede explicar la preeclampsia.</p>

The serum brain-derived neurotrophic factor concentration prior to initiation of an in vitro fertilization cycle predicts outcome

Our objective was to determine if the concentration of circulating brain-derived neurotrophic factor (BDNF) prior to cycle initiation predicts outcome in women undergoing in vitro fertilization (IVF). Stored serum samples from 226 women - 54 with a live birth, 45 with a spontaneous abortion, 38 with a biochemical pregnancy, 54 who did not become pregnant and 35 with an ectopic pregnancy- were retrospectively blindly tested for BDNF by ELISA. The median serum concentration of BDNF was highest in women with an extrauterine ectopic pregnancy (7.3ng/ml), intermediate in women whose embryos did not implant (5.5ng/ml) and lowest in women with a spontaneous abortion (4.2ng/ml), biochemical pregnancy (3.8ng/ml) or a live birth (3.6ng/ml) (P<0.0001). Among women with a positive pregnancy test an elevated BDNF level predicted an ectopic pregnancy with a sensitivity of 0.853 (0.689, 0.950) and a specificity of 0.949 (0.897, 0.979). We conclude that elevated BDNF in serum obtained before IVF cycle initiation is predictive of an extrauterine pregnancy.

BDNF rs6265 methylation and genotype interact on risk for schizophrenia

Epigenetic mechanisms can mediate gene-environment interactions relevant for complex disorders. The BDNF gene is crucial for development and brain plasticity, is sensitive to environmental stressors, such as hypoxia, and harbors the functional SNP rs6265 (Val(66)Met), which creates or abolishes a CpG dinucleotide for DNA methylation. We found that methylation at the BDNF rs6265 Val allele in peripheral blood of healthy subjects is associated with hypoxia-related early life events (hOCs) and intermediate phenotypes for schizophrenia in a distinctive manner, depending on rs6265 genotype: in ValVal individuals increased methylation is associated with exposure to hOCs and impaired working memory (WM) accuracy, while the opposite is true for ValMet subjects. Also, rs6265 methylation and hOCs interact in modulating WM-related prefrontal activity, another intermediate phenotype for schizophrenia, with an analogous opposite direction in the 2 genotypes. Consistently, rs6265 methylation has a different association with schizophrenia risk in ValVals and ValMets. The relationships of methylation with BDNF levels and of genotype with BHLHB2 binding likely contribute to these opposite effects of methylation. We conclude that BDNF rs6265 methylation interacts with genotype to bridge early environmental exposures to adult phenotypes, relevant for schizophrenia. The study of epigenetic changes in regions containing genetic variation relevant for human diseases may have beneficial implications for the understanding of how genes are actually translated into phenotypes.

Long-term effects of early life stress exposure: Role of epigenetic mechanisms

Stress is an adaptive response to demands of the environment and thus essential for survival. Exposure to stress during the first years of life has been shown to have profound effects on the growth and development of an adult individual. There are evidences demonstrating that stressful experiences during gestation or in early life can lead to enhanced susceptibility to mental disorders. Early-life stress triggers hypothalamic-pituitary-adrenocortical (HPA) axis activation and the associated neurochemical reactions following glucocorticoid release are accompanied by a rapid physiological response. An excessive response may affect the developing brain resulting in neurobehavioral and neurochemical changes later in life. This article reviews the data from experimental studies aimed to investigate hormonal, functional, molecular and epigenetic mechanisms involved in the stress response during early-life programming. We think these studies might prove useful for the identification of novel pharmacological targets for more effective treatments of mental disorders.

Reduced Circulating Concentration of Brain-derived Neurotrophic Factor is Associated with Peri- and Post-implantation Failure following In Vitro Fertilization-Embryo Transfer

PROBLEM

We evaluated associations between brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT4) and pregnancy outcome in women undergoing in vitro fertilization-embryo transfer (IVF-ET).

METHOD OF STUDY

Sera obtained on days 24 and 28 of an IVF cycle from women with a live birth, spontaneous abortion, biochemical pregnancy, not pregnant, or an ectopic pregnancy were retrospectively analyzed for BDNF and NT4 by ELISA.

RESULTS

Median BDNF levels were higher in women with a live birth compared to women with an ectopic pregnancy (P < 0.0001), spontaneous abortion (P < 0.0001), or a biochemical pregnancy (P = 0.0004), but not in women who did not become pregnant. NT4 was detected in <25% of sera and did not differ by outcome. There was no association between BDNF level and oocyte or pre-transfer embryo parameters.

CONCLUSION

Decreased circulating BDNF early in an IVF cycle is associated with adverse peri- and/or post-implantation events and subsequent pregnancy failure.

Increased epigenetic alterations at the promoters of transcriptional regulators following inadequate maternal gestational weight gain

Epigenetic modifications are thought to serve as a memory of exposure to in utero environments. However, few human studies have investigated the associations between maternal nutritional conditions during pregnancy and epigenetic alterations in offspring. In this study, we report genome-wide methylation profiles for 33 postpartum placentas from pregnancies of normal and foetal growth restriction with various extents of maternal gestational weight gain. Epigenetic alterations accumulate in the placenta under adverse in utero environments, as shown by application of Smirnov-Grubbs’ outlier test. Moreover, hypermethylation occurs frequently at the promoter regions of transcriptional regulator genes, including polycomb targets and zinc-finger genes, as shown by annotations of the genomic and functional features of loci with altered DNA methylation. Aberrant epigenetic modifications at such developmental regulator loci, if occurring in foetuses as well, will elevate the risk of developing various diseases, including metabolic and mental disorders, later in life.

Regional changes of placental vascularization in preeclampsia: a review

Preeclampsia is characterized by vascular dysfunction and results in maternal and fetal morbidity and mortality. The placenta plays a critical role in the growth and development of the fetus, and recent studies indicate that placental architecture, oxygen availability, and oxidative stress indices vary across different regions of the placenta. Our earlier studies have reported altered maternal angiogenesis and differential placental gene expression and methylation patterns of angiogenic factors in women with preeclampsia when compared with normotensive women. We have also demonstrated lower maternal and placental neurotrophin (NT) levels in women with preeclampsia. Studies suggest that oxidative stress is associated with proteases like matrix metalloproteinases (MMPs) and growth factors like NTs and angiogenic factors known to be involved in the process of angiogenesis. Recently, we have reported regionwise differential oxidative stress, antioxidant enzyme activity, and NT levels in placenta from normotensive control women and women with preeclampsia. The current review describes the regional changes in the placenta and highlights the role of placental oxidative stress in influencing regional differences in the expression of angiogenic factors, MMPs, and NTs. This review discusses the need for further research on various growth factors and proteins involved in the process of placental development across different regions of the placenta. This would help to understand whether regional differences in these factors affect the growth and development of the fetus.

In Utero Fine Particle Air Pollution and Placental Expression of Genes in the Brain-Derived Neurotrophic Factor Signaling Pathway: An ENVIRONAGE Birth Cohort Study

BACKGROUND

Developmental processes in the placenta and the fetal brain are shaped by the same biological signals. Recent evidence suggests that adaptive responses of the placenta to the maternal environment may influence central nervous system development.

OBJECTIVES

We studied the association between in utero exposure to fine particle air pollution with a diameter ≤ 2.5 μm (PM2.5) and placental expression of genes implicated in neural development.

METHODS

Expression of 10 target genes in the brain-derived neurotrophic factor (BDNF) signaling pathway were quantified in placental tissue of 90 mother-infant pairs from the ENVIRONAGE birth cohort using quantitative real-time polymerase chain reaction. Trimester-specific PM2.5 exposure levels were estimated for each mother's home address using a spatiotemporal model. Mixed-effects models were used to evaluate the association between the target genes and PM2.5 exposure measured in different time windows of pregnancy.

RESULTS

A 5-μg/m3 increase in residential PM2.5 exposure during the first trimester of pregnancy was associated with a 15.9% decrease [95% confidence interval (CI): -28.7, -3.2%, p = 0.015] in expression of placental BDNF at birth. The corresponding estimate for synapsin 1 (SYN1) was a 24.3% decrease (95% CI: -42.8, -5.8%, p = 0.011).

CONCLUSIONS

Placental expression of BDNF and SYN1, two genes implicated in normal neurodevelopmental trajectories, decreased with increasing in utero exposure to PM2.5. Future studies are needed to confirm our findings and evaluate the potential relevance of associations between PM2.5 and placental expression of BDNF and SYN1 on neurodevelopment. We provide the first molecular epidemiological evidence concerning associations between in utero fine particle air pollution exposure and the expression of genes that may influence neurodevelopmental processes.

Neurotrophin levels in different regions of the placenta and their association with birth outcome and blood pressure

INTRODUCTION

Our recent study in preeclampsia indicates differential oxidative stress in various regions of the placenta. Oxidative stress is known to influence neurotrophin levels. We therefore hypothesize that placental regional differences in oxidative stress will also lead to differences in neurotrophin levels.

METHODS

The current study examines the levels of neurotrophins, brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in different regions of the placenta in 50 normotensive control women and 47 women with preeclampsia (21 delivering at term and 26 delivering preterm). Placentae were collected from four different regions: central maternal (CM), central fetal (CF), peripheral maternal (PM) and peripheral fetal (PF).

RESULTS

BDNF levels were higher in CF region as compared to CM (p < 0.01), PM (p < 0.01) and PF (p < 0.05) regions of the placenta in the control group. There was no regional change in NGF levels in any of the groups. Analysis between groups indicated higher NGF levels in CM (p < 0.01), PM (p < 0.05) and PF (p < 0.01) regions of preterm preeclampsia group as compared to control. Negative association of NGF levels in CM, CF and PM regions with baby weight and in CF, PM and PF regions with baby length was observed. NGF levels in all four regions were positively associated with systolic blood pressure.

DISCUSSION

Our data indicates regional differences in levels of BDNF only in normotensive control but not in preeclampsia group. Higher NGF levels in preterm preeclampsia may be a response to increased oxidative stress. This may have implications for altered placental development in preeclampsia.

Adverse obstetric and neonatal outcomes in women with mental disorders

The brain and the placenta synthesize identical peptides and proteins, such as brain-derived neurotrophic factor, oxytocin, vascular endothelial growth factor, cortisol, and matrix metalloproteinases. Given the promiscuity between neurochemistry and the mechanism of placentation, it would be expected that mental disorders occurring during pregnancy would increase the risk of adverse obstetric and neonatal outcomes. Indeed, expectant mothers with anxiety disorders, post-traumatic stress disorder, schizophrenia, or depressive disorders are at higher risk of preterm birth, low-birth-weight and small-for-gestational-age infants than controls. These mental illnesses are accompanied by a procoagulant phenotype and low activity of tissue plasminogen activator, which may contribute to placental insufficiency. Another risk factor for pregnancy complications is hyperemesis gravidarum, more common among women with eating disorders or anxiety disorders than in controls. Severe hyperemesis gravidarum is associated with dehydration, electrolyte imbalance and malnutrition, all of which may increase the risk of miscarriages, of low-birth-weight babies and preterm birth. This paper reviews some aspects of mental disorders that may influence pregnancy and neonatal outcomes.

Involvement of Nitric Oxide, Neurotrophins and HPA Axis in Neurobehavioural Alterations Induced by Prenatal Stress

Several studies suggest that negative emotions during pregnancy generate adverse effects on the cognitive, behavioural and emotional development of the descendants. The psychoneuroendocrine pathways involve the transplacentary passage of maternal glucocorticoids in order to influence directly on fetal growth and brain development.Nitric oxide is a gaseous neurotransmitter that plays an important role in the control of neural activity by diffusing into neurons and participates in learning and memory processes. It has been demonstrated that nitric oxide is involved in the regulation of corticosterone secretion. Thus, it has been found that the neuronal isoform of nitric oxide synthase (nNOS) is an endogenous inhibitor of glucocorticoid receptor (GR) in the hippocampus and that nNOS in the hippocampus may participate in the modulation of hypothalamic-pituitary-adrenal axis activity via GR.Neurotrophins are a family of secreted growth factors consisting of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT3) and NT4. Although initially described in the nervous system, they regulate processes such as cell survival, proliferation and differentiation in several other compartments. It has been demonstrated that the NO-citrulline cycle acts together with BDNF in maintaining the progress of neural differentiation.In the present chapter, we explore the interrelation between nitric oxide, glucocorticoids and neurotrophins in brain areas that are key structures in learning and memory processes. The participation of this interrelation in the behavioural and cognitive alterations induced in the offspring by maternal stress is also addressed.

Role of p75 neurotrophin receptor in stem cell biology: more than just a marker

p75(NTR), the common receptor for both neurotrophins and proneurotrophins, has been widely studied because of its role in many tissues, including the nervous system. More recently, a close relationship between p75(NTR) expression and pluripotency has been described. p75(NTR) was shown to be expressed in various types of stem cells and has been used to prospectively isolate stem cells with different degrees of potency. Here, we give an overview of the current knowledge on p75(NTR) in stem cells, ranging from embryonic to adult stem cells, and cancer stem cells. In an attempt to address its potential role in the control of stem cell biology, the molecular mechanisms underlying p75(NTR) signaling in different models are also highlighted. p75(NTR)-mediated functions include survival, apoptosis, migration, and differentiation, and depend on cell type, (pro)neurotrophin binding, interacting transmembrane co-receptors expression, intracellular adaptor molecule availability, and post-translational modifications, such as regulated proteolytic processing. It is therefore conceivable that p75(NTR) can modulate cell-fate decisions through its highly ramified signaling pathways. Thus, elucidating the potential implications of p75(NTR) activity as well as the underlying molecular mechanisms of p75(NTR) will shed new light on the biology of both normal and cancer stem cells.

Levels of brain derived neurotrophic factors across gestation in women with preeclampsia

Preeclampsia (PE) is a major pregnancy complication of placental origin which leads to adverse pregnancy outcome. Brain derived neurotrophic factor (BDNF) is suggested to promote trophoblast growth and regulate placental and fetal development. This study for the first time examines the levels of maternal plasma BDNF at various time points during gestation, cord plasma and placental BDNF levels and their association with birth outcome in women with PE. Normotensive control (NC) women (n=89) and women with PE (n=61) were followed at three different time points [16-20 weeks (T1), 26-30 weeks (T2) and at delivery (T3)]. Maternal blood at all time points and cord blood was collected. Results indicate that maternal BDNF levels at T1 (p=0.050) and T3 (p=0.025) were lower in women with PE than in NC women. Cord BDNF levels at delivery in women with PE were lower (p=0.032) than those in NC women. Placental BDNF gene expression was also lower (p=0.0082) in women with PE than in NC women. Our data suggests that BDNF plays an important role in the development of the materno-fetal-placental unit during pregnancy. Alteration in the levels of BDNF during pregnancy may be associated with an abnormal development of the placenta resulting in PE.

The brain-uterus connection: brain derived neurotrophic factor (BDNF) and its receptor (Ntrk2) are conserved in the mammalian uterus

The neurotrophins are neuropeptides that are potent regulators of neurite growth and survival. Although mainly studied in the brain and nervous system, recent reports have shown that neurotrophins are expressed in multiple target tissues and cell types throughout the body. Additionally, dysregulation of neurotrophins has been linked to several disease conditions including Alzheimer's, Parkinson's, Huntington's, psychiatric disorders, and cancer. Brain derived neurotrophic factor (BDNF) is a member of the neurotrophin family that elicits its actions through the neurotrophic tyrosine receptor kinase type 2 (Ntrk2). Together BDNF and Ntrk2 are capable of activating the adhesion, angiogenesis, apoptosis, and proliferation pathways. These pathways are prominently involved in reproductive physiology, yet a cross-species examination of BDNF and Ntrk2 expression in the mammalian uterus is lacking. Herein we demonstrated the conserved nature of BDNF and Ntrk2 across several mammalian species by mRNA and protein sequence alignment, isolated BDNF and Ntrk2 transcripts in the uterus by Real-Time PCR, localized both proteins to the glandular and luminal epithelium, vascular smooth muscle, and myometrium of the uterus, determined that the major isoforms expressed in the human endometrium were pro-BDNF, and truncated Ntrk2, and finally demonstrated antibody specificity. Our findings suggest that BDNF and Ntrk2 are transcribed, translated, and conserved across mammalian species including human, mouse, rat, pig, horse, and the bat.

The PI3K/Akt signaling pathway exerts effects on the implantation of mouse embryos by regulating the expression of RhoA

The aim of this study was to investigate whether the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway affects the implantation of mouse embryos by regulating the expression of RhoA. The expression of PI3K, Akt, phosphorylated (p-)Akt, phosphatase and tensin homolog (PTEN) and RhoA in the uterus of mice on day 5 of pregnancy (D5) and in pseudopregnant mice was examined by quantitative reverse transcription polymerase chain reaction (qRT-PCR), immunohistochemistry and western blot analysis. A functional analysis of these genes was also performed by the intrauterine injection with the PI3K inhibitor, LY294002, on day 2 of pregnancy (D2). The expression levels of PI3K, p-Akt, RhoA at the implantation site were higher than those at the inter-implantation site in the endometrium; however, opposite effects were observed for PTEN expression. The expression levels of the above genes in the pseudopregnant group and in the group injected with the PI3K/Akt inhibitor, LY294002, were markedly lower than those in the pregnant group. Functional experiments revealed that the number of implantation sites had been significantly decreased (P<0.05) following the intrauterine injection of the PI3K inhibitor, LY294002, on day 2 of gestation compared with the contralateral injection of phosphate-buffered saline (PBS). These results suggest that the PI3K/Akt signaling pathway affects embryo implantation by regulating the expression of RhoA.

Improved efficiency of microsurgical enucleated tripronuclear zygotes development and embryonic stem cell derivation by supplementing epidermal growth factor, brain-derived neurotrophic factor, and insulin-like growth factor-1

Human embryonic stem cells (hESCs) hold great promise for future clinical cell therapies because of their unique potential to differentiate into all human cell types. However, the destruction of normal fertilized embryos and the derivation of hESCs for research has resulted in polarized ethical debates, with most of the controversy centered on embryo destruction. Therefore, due to less ethical controversy surrounding them, abnormal fertilized zygotes that are usually discarded are a potential feasible resource for the derivation of hESCs. Microsurgery on human polyspermic zygotes can contribute to the derivation of hESCs, but the efficiency is much lower. Here, we reported a culture system to enhance the developmental competence of such microsurgical human polyspermic zygotes by EGF-BDNF-IGF-1 combination, which eventually resulted in the increased derivation efficiency of hESCs from them. We found that the developmental efficiency of microsurgical enucleated tripronuclear (3PN) embryos cultured with the EGF-BDNF-IGF-1 combination was significantly increased compared with the control group. More importantly, when the microsurgical enucleated 3PN embryos were cultured in medium supplemented with EGF-BDNF-IGF-1, the frequency ratio of chromosome abnormality was reduced. Our present study will facilitate the development of hESC line derivation in subsequent studies and also provide an additional choice for infertile couples.

Suppression of choriocarcinoma invasion and metastasis following blockade of BDNF/TrkB signaling

Brain-derived neurotrophic factor (BDNF) acts through its cognate receptor tyrosine kinase-B (TrkB) to regulate diverse physiological functions in reproductive and other tissues. In normal and malignant trophoblastic cells, the BDNF/TrkB signaling promotes cell growth. Due to the highly malignant nature of choriocarcinoma, we investigated possible involvement of this system in choriocarcinoma cell invasion and metastasis. We demonstrated that treatment of cultured choriocarcinoma cells, known to express both BDNF and TrkB, with a soluble TrkB ectodomain or a Trk receptor inhibitor K252a suppressed cell invasion accompanied with decreased expression of matrix metalloproteinase-2, a cell invasion marker. In vivo studies using a tumor xenograft model in athymic nude mice further showed inhibition of cell invasion from tumors to surrounding tissues following the suppression of endogenous TrkB signaling. For an in vivo model of choriocarcinoma metastasis, we performed intravenous injections of JAR cells expressing firefly luciferase into severe combined immunodeficiency (SCID) mice. Treatment with K252a inhibited metastasis of tumors to distant organs. In vivo K252a treatment also suppressed metastatic tumor growth as reflected by decreased cell proliferation and increased apoptosis and caspases-3/7 activities, together with reduced tissue levels of a tumor marker, human chorionic gonadotropin-β. In vivo suppression of TrkB signaling also led to decreased expression of angiogenic markers in metastatic tumor, including cluster of differentiation 31 and vascular endothelial growth factor A. Our findings suggested essential autocrine/paracrine roles of the BDNF/TrkB signaling system in choriocarcinoma invasion and metastasis. Inhibition of this signaling could serve as the basis to develop a novel therapy for patients with choriocarcinoma.

Mechanism of pain generation for endometriosis-associated pelvic pain

PURPOSE

Endometriosis-associated pelvic pain appears due to persistent nociceptive stimulation, but the precise mechanisms remain poorly understood.

METHODS

A search was conducted to screen and select articles from PubMed.

MAIN RESULTS

Neurotrophins (NTs), a family of neuronal growth factors, are overexpressed in endometriosis and encompass NGF, BDNF and NT-3 and NT-4/5. NT receptors, TrkA and p75NTR, and NT receptor-interacting proteins, MAGE and NDN, were also expressed. NTs and their receptors play a role in the development and maintenance of neural tissues in non-neuronal cell types such as endometriosis. Nerve fibers contain unmyelinated sensory C, myelinated sensory Adelta and adrenergic nerve fibers that innervate abnormal cell growths. An increased release of proinflammatory cytokines from endometriotic lesions is responsible for the excessive sensory innervation and development of chronic pelvic pain.

CONCLUSIONS

The preponderance of the inflammatory milieu and subsequent hyperinnervation might be involved in the pathophysiology of pain generation in women with endometriosis.

Differential regulation of brain-derived neurotrophic factor in term and preterm preeclampsia

Our earlier studies in preeclampsia (PE) suggest a causal relationship between altered angiogenic factors and birth outcomes. Recent studies suggest that brain-derived neurotrophic factor (BDNF) can stimulate angiogenesis. The present study examines the levels of maternal and cord BDNF in women with PE (n = 106; full term [n = 60] and preterm [n = 46]) and normotensive women (n = 95; control) delivering at term. Maternal BDNF levels were lower (P < .05) in women with PE when compared to normotensive women. Cord BDNF levels were higher (P < .01) in women with PE delivering at term, while it was lower (P < .01) in women delivering preterm. Maternal BDNF levels were negatively associated with systolic and diastolic blood pressure (P < .01 for both). Our data for the first time suggest a possible role for BDNF in the pathophysiology of PE. Differential regulation of cord BDNF levels in preterm PE suggests a need to follow-up children to assess the neurodevelopmental effects in later life.

Altered expression of norepinephrine transporter and norepinephrine in human placenta cause pre-eclampsia through regulated trophoblast invasion

Objective

We investigated the norepinephrine transporter (NET) expression in normal and pre-eclamptic placentas and analyzed the invasion activity of trophoblastic cells based on norepinephrine (NE)-NET regulation.

Methods

NET and NE expression levels were examined by western blot and enzyme-linked immunosorbent assay, respectively. Trophoblast invasion activity, depending on NE-NET regulation, was determined by NET-small interfering RNA (siRNA) and NET transfection into the human extravillous trophoblast cells with or without NE treatment and invasion rates were analyzed by zymography and an invasion assay.

Results

NET mRNA was expressed at a low level in pre-eclamptic placentas compared with normal placentas and NE concentration in maternal plasma increased significantly in pre-eclamptic women compared to normal pregnant women (p<0.05). NET gene upregulation and NE treatment stimulated trophoblast cell invasion up to 2.5-fold (p<0.05) by stimulating matrix metalloproteinase-9 activity via the phosphoinositol-3-kinase/AKT signaling pathway, whereas NET-siRNA with NE treatment reduced invasion rates.

Conclusion

NET expression is reduced by inadequate regulation of NE levels during placental development. This suggests that a complementary balance between NET and NE regulates trophoblast cell invasion activities during placental development.

Higher levels of brain derived neurotrophic factor but similar nerve growth factor in human milk in women with preeclampsia

Children born to mothers with preeclampsia have consistently been suggested to be at risk for cognitive and behavioral disorders in later life. Breastfeeding is said to be associated with better neurodevelopment outcomes. Our earlier studies indicated higher levels of docosahexaenoic acid (DHA) in human milk in women with preeclampsia. DHA is known to regulate the expression of neurotrophins and together they play a vital role in neurodevelopment and cognitive performance. The present study examines the levels of maternal plasma and milk neurotrophins [(nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF)] in women with preeclampsia and compares them with normotensive women who served as controls. Singleton pregnant women diagnosed with preeclampsia (n=72) and controls (n=102) were recruited for this study from Bharati Hospital, Pune. Plasma and milk samples were analyzed for NGF and BDNF levels using the Emax Immuno Assay System using promega kits. Maternal plasma NGF and BDNF levels were lower (p<0.01 for both) in women with preeclampsia as compared to the control women. Milk NGF levels were similar while milk BDNF levels were higher (p<0.05) in the preeclampsia group as compared to controls. Plasma NGF levels were positively correlated with milk NGF levels in the control group. Our results indicate the differential regulation of milk NGF and BDNF levels in women with preeclampsia. The present study suggests a role for both NGF and BDNF in human milk for postnatal brain development. Further studies need to examine the associations of DHA and BDNF in human milk with cognition at later ages.

The tyrosine phosphatase SHP-1 negatively regulates cytotrophoblast proliferation in first-trimester human placenta by modulating EGFR activation

Insulin-like growth factors (IGFs) influence placental cell (cytotrophoblast) kinetics. We recently reported that the protein tyrosine phosphatase (PTP) SHP-2 positively regulates IGF actions in the placenta. In other systems, the closely related PTP, SHP-1, functions as a negative regulator of signaling events but its role in the placenta is still unknown. We examined the hypothesis that SHP-1 negatively regulates IGF actions in the human placenta. Immunohistochemical (IHC) analysis demonstrated that SHP-1 is abundant in cytotrophoblast. SHP-1 expression was decreased in first-trimester placental explants using siRNA; knockdown did not alter IGF-induced proliferation but it significantly enhanced proliferation in serum-free conditions, revealing that placental growth is endogenously regulated. Candidate regulators were determined by using antibody arrays, Western blotting, and IHC to examine the activation status of multiple receptor tyrosine kinases (RTKs) in SHP-1-depleted explants; amongst the alterations observed was enhanced activation of EGFR, suggesting that SHP-1 may interact with EGFR to inhibit proliferation. The EGFR tyrosine kinase inhibitor PD153035 reversed the elevated proliferation seen in the absence of SHP-1. This study demonstrates a role for SHP-1 in human trophoblast turnover and establishes SHP-1 as a negative regulator of EGFR activation. Targeting placental SHP-1 expression may provide therapeutic benefits in common pregnancy conditions with abnormal trophoblast proliferation.

Promotion of human early embryonic development and blastocyst outgrowth in vitro using autocrine/paracrine growth factors

Studies using animal models demonstrated the importance of autocrine/paracrine factors secreted by preimplantation embryos and reproductive tracts for embryonic development and implantation. Although in vitro fertilization-embryo transfer (IVF-ET) is an established procedure, there is no evidence that present culture conditions are optimal for human early embryonic development. In this study, key polypeptide ligands known to be important for early embryonic development in animal models were tested for their ability to improve human early embryo development and blastocyst outgrowth in vitro. We confirmed the expression of key ligand/receptor pairs in cleavage embryos derived from discarded human tri-pronuclear zygotes and in human endometrium. Combined treatment with key embryonic growth factors (brain-derived neurotrophic factor, colony-stimulating factor, epidermal growth factor, granulocyte macrophage colony-stimulating factor, insulin-like growth factor-1, glial cell-line derived neurotrophic factor, and artemin) in serum-free media promoted >2.5-fold the development of tri-pronuclear zygotes to blastocysts. For normally fertilized embryos, day 3 surplus embryos cultured individually with the key growth factors showed >3-fold increases in the development of 6-8 cell stage embryos to blastocysts and >7-fold increase in the proportion of high quality blastocysts based on Gardner's criteria. Growth factor treatment also led to a 2-fold promotion of blastocyst outgrowth in vitro when day 7 surplus hatching blastocysts were used. When failed-to-be-fertilized oocytes were used to perform somatic cell nuclear transfer (SCNT) using fibroblasts as donor karyoplasts, inclusion of growth factors increased the progression of reconstructed SCNT embryos to >4-cell stage embryos. Growth factor supplementation of serum-free cultures could promote optimal early embryonic development and implantation in IVF-ET and SCNT procedures. This approach is valuable for infertility treatment and future derivation of patient-specific embryonic stem cells.

Suppression of hydatidiform molar growth by inhibiting endogenous brain-derived neurotrophic factor/tyrosine kinase B signaling

Brain-derived neurotrophic factor (BDNF)/tyrosine kinase B (TrkB) receptor signaling promotes trophoblast growth in normal and abnormal pregnancy. It also regulates the growth of malignant trophoblastic, choriocarcinoma cells. However, possible involvement of this signaling system in hydatidiform mole, another major gestational trophoblastic disease, has not been determined. Here, we found the expression of BDNF in syncytiotrophoblasts and its receptor, TrkB, in cytotrophoblasts of hydatidiform mole using real-time RT-PCR and immunoassays. In molar explant cultures, treatment with soluble TrkB ectodomain or a Trk receptor inhibitor K252a inhibited trophoblast outgrowth as well as decreased cytotrophoblast proliferation and cellular viability based on histopathological analyses and glucose metabolism monitoring. These inhibitors also increased apoptosis and caspase-3/7 activities. In an in vivo model of hydatidiform molar growth based on xenotransplantation of molar tissues into kidney capsules of SCID mice, treatment with K252a suppressed molar growth as reflected by decreased trophoblast proliferation and their invasion into mouse kidney, reduced tissue levels of chorionic gonadotropin-β, and increased apoptosis. Based on PCR array analyses to identify changes in expression profiles of cell cycle- and apoptosis-related genes in cultured molar explants, suppression of endogenous TrkB signaling led to decreases in key cell cycle-stimulatory and checkpoint genes together with the down-regulation of different antiapoptotic genes. Our findings demonstrate the importance of paracrine signaling by the BDNF/TrkB system in the proliferation and survival of molar trophoblasts. Inhibition of BDNF/TrkB signaling could provide a novel medical treatment for hydatidiform mole.

Inhibition of uterine sarcoma cell growth through suppression of endogenous tyrosine kinase B signaling

Uterine leiomyosarcoma is an aggressive tumor typically found at advanced stages due to difficulties with early diagnosis. Because uterine leiomyosarcoma is resistant to conventional radiation and chemotherapy, the development of more potent medical therapeutics is anticipated. Using quantitative real-time RT-PCR and immunostaining, we found the expression of brain-derived neurotrophic factor (BDNF) and neurotropin-4/5, together with their receptor, tyrosine kinase B (TrkB), in different uterine sarcoma cell lines and primary tumor samples from uterine leiomyosarcoma patients. We noted that levels of BDNF were more abundant than those of neurotropin-4/5. Moreover, the expression of TrkB and its ligands was elevated in a multidrug-resistant cell line and samples obtained from patients with leiomyosarcoma. In cultured uterine sarcoma cells, inhibition of endogenous TrkB signaling by treatment with either the soluble TrkB ectodomain or the Trk receptor inhibitor, K252a, suppressed cell proliferation and increased apoptosis based on cell viability and proliferation, in situ terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate nick end-labeling and caspase-3/7 assays, whereas an inactive plasma membrane nonpermeable K252b was ineffective. Correspondingly, treatment with exogenous BDNF increased cell proliferation. In in vivo studies in athymic nude mice bearing multidrug-resistant uterine sarcoma cell tumors, we demonstrate suppression of tumor growth by treatment with K252a, but not K252b, as reflected by decreased cell proliferation and increased levels of apoptosis and caspase-3/7 activities without obvious side effects. Our findings indicated that endogenous signaling of the TrkB pathway contributed to uterine sarcoma cell growth, and inhibition of TrkB signaling in these tumors could provide a novel medical therapy for patients with uterine sarcomas.

Gastrocnemius-derived BDNF promotes motor function recovery in spinal cord transected rats

This study evaluated the role of gastrocnemius-derived brain-derived neurotrophic factor (BDNF) and possible mechanism in motor improvement in T10 spinal cord transection (SCT) rats. There was complete paralysis in hindlimbs immediately after SCT, followed by partial functional restoration with time going. The level of BDNF but not its mRNA gradually increased in caudal stump after SCT, whereas a significant increase in both BDNF and its mRNA was simultaneously seen in gastrocnemius. Injection of BDNF antibody into the gastrocnemius significantly decreased hindlimb locomotor function, downregulated the level of BDNF and its mRNA together with extracellular signal-regulated kinase 1/2 (Erk1/2). Moreover, ventral root ligation led to decrease both BDNF and Erk in caudal stump, indicating BDNF transportation from gastrocnemius into the spinal cord. We concluded that gastrocnemius-derived BDNF reduced motor functional deficits in SCT rats through Erk signaling pathway. These novel findings suggested the usage of BDNF in muscle for the treatment of spinal cord injury in clinic.

Association of brain-derived neurotrophic factor and tyrosine kinase B receptor in pregnancy

Abnormal brain development in a compromised prenatal and/or early postnatal environment is thought to be a risk factor for several neurobehavioural disorders. However, the mechanisms underlying these are not well understood. We have earlier reported reduced placental docosahexaenoic acid (DHA) levels in preterm deliveries. We have hypothesized that increased oxidative stress and reduced DHA levels may lead to changes in the circulating levels of maternal and cord brain-derived neurotrophic factor (BDNF) and its receptor tyrosine kinase B (TrkB) levels. A total number of 96 women delivering preterm and 95 women delivering at term were recruited. Plasma BDNF levels were measured in both mother and cord blood plasma using the BDNF Immuno Assay kit. Placental TrkB levels were analysed using sandwich enzyme-linked immunosorbent assay (ELISA). Maternal plasma BDNF levels and placental TrkB levels were higher (p<0.05) while cord plasma BDNF levels were lower (p<0.01) in women delivering preterm as compared to term. There was a negative association between levels of placental TrkB and DHA (p=0.034). A negative association between maternal plasma BDNF levels and placental weight (p=0.001) was observed while a positive association was seen between cord plasma BDNF levels and gestation (p=0.025). The reduction in cord BDNF levels may have implications for altered neurodevelopment in childhood and later life. Studies need to be undertaken to follow up children born preterm for risk of neurobehavioural disorders like attention deficit hyperactivity disorder (ADHD) to understand the effect of altered BDNF at birth on neurodevelopment.

Brain-derived neurotrophic factor from follicular fluid is positively associated with rate of mature ooocytes collected and cleavage rate in intracytoplasmic sperm injection patients

PURPOSE

The aim of the study was to evaluate the correlation between BDNF and oocyte maturation and to verify whether BDNF could predict in vitro fertilization (IVF) outcome.

METHODS

The follicle fluid (FF) for BDNF, E(2) and P assay were obtained from 59 patients undergoing intracytoplasmic sperm injection (ICSI). The women were divided into two groups by pregnancy outcome and their clinical and lab data were compared. And the correlation of BDNF with E(2), P, age, and IVF data were analyzed.

RESULTS

Positive correlation was observed between BDNF and E(2) concentration in FF. BDNF was positively correlated with the rate of mature oocytes collected and cleavage rate.

CONCLUSIONS

The BDNF in FF could not predict IVF outcome, but BDNF in FF might play an important role in the maturation of oocyte and development of oocyte into preimplantation embryo.

Transcriptomic analysis brings new insight into the biological role of the prion protein during mouse embryogenesis

The biological function of the Prion protein remains largely unknown but recent data revealed its implication in early zebrafish and mammalian embryogenesis. To gain further insight into its biological function, comparative transcriptomic analysis between FVB/N and FVB/N Prnp knockout mice was performed at early embryonic stages. RNAseq analysis revealed the differential expression of 73 and 263 genes at E6.5 and E7.5, respectively. The related metabolic pathways identified in this analysis partially overlap with those described in PrP1 and PrP2 knockdown zebrafish embryos and prion-infected mammalian brains and emphasize a potentially important role for the PrP family genes in early developmental processes.

Brain-derived neurotrophic factor/tyrosine kinase B signaling regulates human trophoblast growth in an in vivo animal model of ectopic pregnancy

Although medical treatment of unruptured ectopic pregnancy using methotrexate has been established, development of more potent and safer medical treatment is needed due to limited indications and side effects of methotrexate. Brain-derived neurotrophic factor (BDNF) signals through its receptor tyrosine kinase B (TrkB) to regulate the growth of malignant trophoblastic, choriocarcinoma cell. We investigated possible involvement of this signaling system in nonmalignant human trophoblast growth in both ectopic and intrauterine pregnancy. Here, we demonstrated the expression of BDNF in syncytiotrophoblasts and extravillous trophoblasts (EVTs) together with TrkB in cytotrophoblasts and EVTs in human placental villi during both normal and ectopic pregnancies. Treatment of cultured villous explants with soluble TrkB ectodomain or a Trk receptor inhibitor K252a suppressed cytotrophoblast differentiation by inhibiting EVT outgrowth reflected by decreased levels of an EVT marker, human leukocyte antigen-G. These inhibitors also decreased cytotrophoblast proliferation and cellular viability based on histopathological analyses and monitoring glucose metabolism, together with increased apoptosis in cytotrophoblasts based on in situ terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end-labeling and caspase-3/7 assays. After xenotransplantation of human placental villi into SCID mice as an in vivo model of ectopic pregnancy, treatment with K252a suppressed transplanted villi growth as reflected by decreased cytotrophoblast differentiation and proliferation, reduced tissue levels of chorionic gonadotropin-β, and increased apoptosis and caspase-3/7 activities. Thus, paracrine signaling by the BDNF/TrkB system is important for human cytotrophoblast differentiation, proliferation, and survival, and inhibition of BDNF/TrkB signaling in cytotrophoblasts could provide a novel medical treatment for ectopic pregnancy.