Development Of Apoptosis Research Articles

Loss of non-canonical KCC2 functions promotes developmental apoptosis of cortical projection neurons.

KCC2, encoded in humans by the SLC12A5 gene, is a multifunctional neuron-specific protein initially identified as the chloride (Cl- ) extruder critical for hyperpolarizing GABAA receptor currents. Independently of its canonical function as a K-Cl cotransporter, KCC2 regulates the actin cytoskeleton via molecular interactions mediated through its large intracellular C-terminal domain (CTD). Contrary to the common assumption that embryonic neocortical projection neurons express KCC2 at non-significant levels, here we show that loss of KCC2 enhances apoptosis of late-born upper-layer cortical projection neurons in the embryonic brain. In utero electroporation of plasmids encoding truncated, transport-dead KCC2 constructs retaining the CTD was as efficient as of that encoding full-length KCC2 in preventing elimination of migrating projection neurons upon conditional deletion of KCC2. This was in contrast to the effect of a full-length KCC2 construct bearing a CTD missense mutation (KCC2R952H ), which disrupts cytoskeletal interactions and has been found in patients with neurological and psychiatric disorders, notably seizures and epilepsy. Together, our findings indicate ion transport-independent, CTD-mediated regulation of developmental apoptosis by KCC2 in migrating cortical projection neurons.

Progesterone receptor membrane component 1 (PGRMC1)-mediated progesterone effect on preimplantation development of in vitro produced porcine embryos

Progesterone is a steroid hormone well known for its significant role in the reproduction process of mammals. Numerous studies have reported on the regulation of progesterone during implantation, pregnancy and parturition, but there are fewer studies on progesterone in relation to the early stages of embryo development. In the present study, we investigated the effects of progesterone during the development of in vitro produced porcine embryos. First, gene expression of various progesterone receptors in the in vitro produced porcine embryos were analyzed. PGRMC1 and PGRMC2 (progesterone receptor membrane component 1 and 2) showed distinct expression. Next, the embryos were treated with two concentrations of progesterone (10 nM and 100 nM) for two different durations (from day 0 and from day 4) to compare the developmental rates, cell numbers, and apoptosis rates of day 7 blastocysts. The experimental groups in both durations showed similarly increased blastocyst cell numbers and decreased apoptosis rates when treated with 100 nM progesterone. Furthermore, the expression levels of PGRMC1, PGRMC2, PAIRBP1 (plasminogen activator inhibitor RNA-binding protein 1), and apoptosis-related genes were examined in blastocysts and showed significant increases in the 100 nM treatment group compared to the control group. Subsequently, the embryos were treated with the PGRMC1 inhibitor, AG-205, and developmental rates, cell numbers, and apoptosis rates of day 7 blastocysts were compared. In addition, 100 nM progesterone was treated simultaneously with AG-205 to test if the inhibition effect is relieved by progesterone. Groups treated with 1 μM and 2 μM AG-205 showed decreased cell numbers and increased apoptosis rates in day 7 blastocysts compared to the control group. We also confirmed the recovery of inhibition by 100 nM progesterone. In conclusion, the present study indicated that progesterone positively affects the development of in vitro produced preimplantation porcine embryos by increasing cell proliferation and decreasing apoptosis via PGRMC1-involved actions. However, the detailed mechanisms of PGRMC1 need further elucidation.

Programmed cell death along the midline axis patterns ipsilaterality in gastrulation.

Bilateral symmetry is the predominant body plan in the animal kingdom. Cells on the left and right sides remain compartmentalized on their ipsilateral side throughout life, but with occasional variation, as evidenced by gynandromorphs and human disorders. How this evolutionarily conserved body plan is programmed remains a fundamental yet unanswered question. Here, we show that germ-layer patterning in avian gastrulation is ipsilateral despite cells undergoing highly invasive mesenchymal transformation and cell migration. Contralateral invasion is suppressed by extracellular matrix (ECM) and programmed cell death (PCD) along the embryonic midline. Ipsilateral gastrulation was lost by midline ECM and PCD inhibition but restored with exogenously induced PCD. Our data support ipsilaterality as an integral component of bilaterality and highlight a positive functional role of PCD in development.

Restraint stress and elevation of corticotrophin-releasing hormone in female mice impair oocyte competence through activation of the tumour necrosis factor α (TNF-α) system.

Studies have observed that restraint stress (RS) and the associated elevation in corticotrophin-releasing hormone (CRH) impair oocyte competence by triggering apoptosis of ovarian cells but the underlying mechanisms are largely unclear. Although one study demonstrated that RS and CRH elevation triggered apoptosis in ovarian cells and oocytes via activating Fas/FasL signalling, other studies suggested that RS might damage cells by activating other pathways as well as Fas signalling. The objective of this study was to test whether RS and CRH elevation impairs oocytes by activating tumour necrosis factor α (TNF-α) signalling. Our invivo experiments showed that RS applied during oocyte prematuration significantly increased expression of TNF-α and its receptor (TNFR1) while inducing apoptosis in both oocytes and mural granulosa cells (MGCs). Invitro treatment of MGCs with CRH significantly increased their apoptotic percentages and levels of TNF-α and TNFR1 expression. Invitro knockdown by interfering RNA, invivo knockout of the TNF-α gene or injection of TNF-α antagonist etanercept significantly relieved the adverse effects of RS and CRH on apoptosis of MGCs and/or the developmental potential and apoptosis of oocytes. The results suggest that RS and CRH elevation in females impair oocyte competence through activating TNF-α signalling and that a TNF-α antagonist might be adopted to ameliorate the adverse effects of psychological stress on oocytes.

Roots and stems of Kadsura coccinea extract induced developmental toxicity in zebrafish embryos/larvae through apoptosis and oxidative stress

Context Although the roots and stems of Kadsura coccinea (Lem.) A. C. Smith. [Schisandraceae] are herbs and traditional foods in Li nationality, its toxicity remains unclear. Objective To study developmental toxicity of K. coccinea consumption and explain underlying mechanisms. Materials and methods Zebrafish were applied to assess LC50 values of hydroethanol extract (KCH) and water extract (KCW) of Kadsura coccinea. In further study, three concentrations groups of KCH (3.75, 7.5 and 15 μg/mL for embryo, 7.5, 15 and 30 μg/mL for larvae) and control group (n = 30) were administered. At specific stages of zebrafish development, spontaneous movement, hatching rate, etc., were measured. Gene expressions related to developmental toxicity were examined. Results The LC50 value of KCH (24 or 45 μg/mL) was lower than KCW (1447 or 2011 μg/mL) in embryos or larvae. The inhibited spontaneous movement (20%), hatching rate (20%), body length (12%) and eye area (30%) were observed after KCH treatment. Moreover, the decreased liver areas (25%) and fluorescence intensity (33%), increased ALT (37%) and AST levels (42%) were found in larvae treated with KCH (30 μg/mL). The increased ROS (89%), MDA concentrations (30%), apoptosis generation (62%) and decreased T-SOD activity (16%) were also observed. The represented genes of developmental hepatotoxicity, oxidative stress and apoptosis in zebrafish were activated after KCH (15 or 30 μg/mL) treatment. Discussion and conclusions These results demonstrate that KCH has developmental toxicity on zebrafish. Our study provides a scientific basis for further research on the toxicity of Kadsura coccinea.

Vps13 is required for timely removal of nurse cell corpses.

Programmed cell death and consecutive removal of cellular remnants is essential for development. During late stages of Drosophila melanogaster oogenesis, the small somatic follicle cells that surround the large nurse cells promote non-apoptotic nurse cell death, subsequently engulf them, and contribute to the timely removal of nurse cell corpses. Here, we identify a role for Vps13 in the timely removal of nurse cell corpses downstream of developmental programmed cell death. Vps13 is an evolutionarily conserved peripheral membrane protein associated with membrane contact sites and lipid transfer. It is expressed in late nurse cells, and persistent nurse cell remnants are observed when Vps13 is depleted from nurse cells but not from follicle cells. Microscopic analysis revealed enrichment of Vps13 in close proximity to the plasma membrane and the endoplasmic reticulum in nurse cells undergoing degradation. Ultrastructural analysis uncovered the presence of an underlying Vps13-dependent membranous structure in close association with the plasma membrane. The newly identified structure and function suggests the presence of a Vps13-dependent process required for complete degradation of bulky remnants of dying cells.

Identification of key genes and transcription factors in ageing Arabidopsis papilla cells by transcriptome analysis

Programmed cell death (PCD) play essential roles in plant growth and development. Stigmatic papilla cells form an indispensable organ for plant reproduction. The lifetime of papilla cells is tightly controlled, and the developmental PCD (dPCD) process is involved in papilla cell death. Hence, papilla cell death is a good model for studying on PCD process. In this study, the dPCD signal was visualized in dying papilla cells by detecting the GUS signal of the PCD-related reporter gene BIFUNCTIONAL NUCLEASE 1 (BFN1). We found that the GUS was not expressed at young stage, but strongly expressed in papilla cells at the ageing stage, indicating the PCD process was triggered to terminate the papilla cell fate. Given this, the RNA-Seq data set, which covered the information of the whole lifespan of papilla cells, was analyzed aiming to understand which genes and pathways were involved in papilla cell death. 37 differential expressed genes (DEGs) were isolated. Moreover, the pathways related to energy production and transportation, autophagy, and plant hormone signal transduction were considered as the key pathways involved in the papilla cell death. 9 types, total of 104 transcriptional factors (TFs) were identified as well. Finally, a putative working model of papilla cell death was integrated. The findings herein will enrich the knowledge of the dPCD-mediated pathway in regulating plant organ/tissue growth, development, senescence, and death. Our study will provide some referential gene resources for studying on the dPCD in other plant organs or tissues.

Bisphenol F-Induced Neurotoxicity toward Zebrafish Embryos.

In this study, the influence of bisphenol F (BPF) toward central nervous system (CNS) was assessed using zebrafish embryos. We found that BPF could induce significant neurotoxicity toward zebrafish embryos, including inhibited locomotion, reduced moving distance, and CNS cell apoptosis at an effective concentration of 0.0005 mg/L. Immunofluorescence assay showed that both microglia and astrocyte in zebrafish brain were significantly activated by BPF, indicating the existence of neuroinflammatory response. Peripheral motor neuron development was significantly inhibited by BPF at 72 hpf. RNA-seq data indicated that neuronal developmental processes and cell apoptosis pathways were significantly affected by BPF exposure, which was consistent with the phenotypic results. Chip-seq assay implied that the transcriptional changes were not mediated by ERα. Additionally, no significant change was found in neurotransmitter levels (5-hydroxytryptamine, dopamine, and acetylcholine) or acetylcholinesterase (Ache) enzyme activity after BPF exposure, indicating that BPF may not affect neurotransmission. In conclusion, BPF could lead to abnormal neural outcomes during zebrafish early life stage through inducing neuroinflammation and CNS cell apoptosis even at environmentally relevant concentration.

The Function of Autophagy in Lace Plant Programmed Cell Death.

The lace plant (Aponogeton madagascariensis) is an aquatic monocot that utilizes programmed cell death (PCD) to form perforations throughout its mature leaves as part of normal development. The lace plant is an emerging model system representing a unique form of developmental PCD. The role of autophagy in lace plant PCD was investigated using live cell imaging, transmission electron microscopy (TEM), immunolocalization, and in vivo pharmacological experimentation. ATG8 immunostaining and acridine orange staining revealed that autophagy occurs in both healthy and dying cells. Autophagosome-like vesicles were also found in healthy and dying cells through ultrastructural analysis with TEM. Following autophagy modulation, there was a noticeable increase in vesicles and vacuolar aggregates. A novel cell death assay utilizing lace plant leaves revealed that autophagy enhancement with rapamycin significantly decreased cell death rates compared to the control, whereas inhibition of autophagosome formation with wortmannin or blocking the degradation of cargoes with concanamycin A had an opposite effect. Although autophagy modulation significantly affected cell death rates in cells that are destined to die, neither the promotion nor inhibition of autophagy in whole plants had a significant effect on the number of perforations formed in lace plant leaves. Our data indicate that autophagy predominantly contributes to cell survival, and we found no clear evidence for its direct involvement in the induction of developmental PCD during perforation formation in lace plant leaves.

Comparative transcriptomic analysis and structure prediction of novel Newt proteins.

Notophthalmus viridescens (Red-spotted Newt) possess amazing capabilities to regenerate their organs and other tissues. Previously, using a de novo assembly of the newt transcriptome combined with proteomic validation, our group identified a novel family of five protein members expressed in adult tissues during regeneration in Notophthalmus viridescens. The presence of a putative signal peptide suggests that all these proteins are secretory in nature. Here we employed iterative threading assembly refinement (I-TASSER) server to generate three-dimensional structure of these novel Newt proteins and predicted their function. Our data suggests that these proteins could act as ion transporters, and be involved in redox reaction(s). Due to absence of transgenic approaches in N. viridescens, and conservation of genetic machinery across species, we generated transgenic Drosophila melanogaster to misexpress these genes. Expression of 2775 transcripts were compared between these five newly identified Newt genes. We found that genes involved in the developmental process, cell cycle, apoptosis, and immune response are among those that are highly enriched. To validate the RNA Seq. data, expression of six highly regulated genes were verified using real time Quantitative Polymerase Chain Reaction (RT-qPCR). These graded gene expression patterns provide insight into the function of novel protein family identified in Newt, and layout a map for future studies in the field.

Dietary L-arginine supplementation during early gestation of gilts affects conceptuses development

l-arginine supplementation of sows has led to improvement of reproductive performance, but the mechanisms responsible for the positive effects of arginine during gestation on conceptuses survival and development are still poorly understood. Thus, we aimed to evaluate effects of 1.0% l-arginine supplementation (ARG) on phenotypic traits of commercial gilts, embryos and fetuses, concentration of gilts’ blood metabolites, expression of developmental and cellular apoptosis genes in conceptuses of 25 and 35 days. At 25 days, IGF1 gene was more expressed in embryos from ARG than in embryos from control gilts (CON) (P = 0.05). At this same gestational age, ARG embryos tended to be heavier compared to CON (P = 0.07) and ARG gilts showed a trend to have a greater arginine concentration in blood plasma (P = 0.06). However, at 35 days of gestation, arginine concentration in blood plasma of ARG gilts tended to be lower compared to CON (P = 0.06) and ARG fetuses showed smaller cephalic-caudal length (P = 0.05). These results indicate that duration of supplementation is determinant for arginine effects, not only on the females performance but also on the conceptuses, since supplementation upregulated IGF1 expression at 25 days, in addition to the reduction of cephalic-caudal length of 35-day fetuses.

Decoupling developmental apoptosis and neuroblast proliferation in Drosophila

Cell proliferation and cell death are opposing but fundamental aspects of development that must be tightly controlled to ensure proper tissue organization and organismal health. Developmental apoptosis of abdominal neuroblasts in the Drosophila ventral nerve cord is controlled by multiple upstream spatial and temporal signals, which have also been implicated in control of cell proliferation. It has therefore remained unclear whether developmental apoptosis is linked to active cell proliferation. Previous investigations into this topic have focused on the effect of cell cycle arrests on exogenous induction of apoptosis, and thus have not addressed whether potential effects of the cell cycle lie with the sensing of damage signals or the execution of apoptosis itself. In this report, we show that developmental apoptosis is not inhibited by cell cycle arrest, and that endogenous cell death occurs independently of cell cycle phase. We also find that ectopic neuroblasts rescued from cell death retain the competency to respond to quiescence cues at the end of embryogenesis. In addition, we observe multiple quiescence types in neuroblasts, and we show that cell death mutant embryos display a specific loss of presumptive G2 quiescent abdominal neuroblasts at the end of embryogenesis. This study demonstrates that upstream control of neuroblast proliferation and apoptosis represent independent mechanisms of regulating stem cell fate, and that execution of apoptosis occurs in a cell cycle-independent manner. Our findings also indicate that a subset of G2Q-fated abdominal neuroblasts are eliminated from the embryo through a non-apoptotic mechanism.

Developmental Apoptosis Promotes a Disease-Related Gene Signature and Independence from CSF1R Signaling in Retinal Microglia

SUMMARYMicroglia have important remodeling functions in neurodevelopment, aging, and disease, with evidence for molecular diversity. However, the signaling pathways and environmental cues that drive diverse states of microglia are incompletely understood. We profiled microglia of a discrete developing CNS region, the murine retina. We found distinct transcriptional signatures for retinal microglia across development and peak postnatal density of a population that resembles aging and disease-associated microglia (DAM) and CD11c+ microglia of developing white matter. While TREM2 signaling modulates the expression of select genes, the DAM-related signature is significantly reduced in retinas lacking Bax, a proapoptotic factor required for neuronal death. Furthermore, we found postnatal retinal microglia highly expressing CD11c are resistant to loss or inhibition of colony stimulating factor 1 receptor (CSF1R), while most microglia can be eliminated in Bax knockout retina. Thus, developmental apoptosis promotes a microglia gene signature linked to CSF1R independence that shares features with microglia in developing white matter and in disease.

Lysosomal Machinery Drives Extracellular Acidification to Direct Non-apoptotic Cell Death

SUMMARYCell death is a fundamental aspect of development, homeostasis, and disease; yet, our understanding of non-apoptotic forms of cell death is limited. One such form is phagoptosis, in which one cell utilizes phagocytosis machinery to kill another cell that would otherwise continue living. We have previously identified a non-autonomous requirement of phagocytosis machinery for the developmental programmed cell death of germline nurse cells in the Drosophila ovary; however, the precise mechanism of death remained elusive. Here, we show that lysosomal machinery acting in epithelial follicle cells is used to non-autonomously induce the death of nearby germline cells. Stretch follicle cells recruit V-ATPases and chloride channels to their plasma membrane to extracellularly acidify the germline and release cathepsins that destroy the nurse cells. Our results reveal a role for lysosomal machinery acting at the plasma membrane to cause the death of neighboring cells, providing insight into mechanisms driving non-autonomous cell death.

Plant proteases during developmental programmed cell death.

Proteases are among the key regulators of most forms of programmed cell death (PCD) in animals. Many PCD processes have also been associated with protease expression or activation in plants, However, functional evidence for the roles and actual modes of action of plant proteases in PCD remains surprisingly limited. In this review, we provide an update on protease involvement in the context of developmentally regulated plant PCD. To illustrate the diversity of protease functions, we focus on several prominent developmental PCD processes, including xylem and tapetum maturation, suspensor elimination, endosperm degradation, and seed coat formation, as well as plant senescence processes. Despite the substantial advances in the field, protease functions are often only correlatively linked to developmental PCD, and the specific molecular roles of proteases in many developmental PCD processes remain to be elucidated.

Developmental toxicity and apoptosis in zebrafish embryos induced by low-dose γ-ray irradiation.

In this paper, the developmental toxicity and apoptosis in zebrafish (Danio rerio) embryos induced by 0.01, 0.05, and 0.10-Gy γ-ray irradiation were investigated and verified by single cell gel electrophoresis, acridine orange staining, flow cytometry, transmission electron microscopy, digital gene expression sequencing, and Western blot analysis. DNA damage, deformity rates, and apoptosis of zebrafish embryos were found to increase significantly with the increase of irradiation dose, and survival and hatching rates significantly decreased when the irradiation dose exceeds 0.10 and 0.05Gy, respectively. Exposure to 0.10-Gy γ-ray irradiation resulted in the swelling of cell mitochondria of zebrafish embryos and changes in their intracellular vacuoles. mRNA and protein expression levels of Shh (sonic hedgehog 19KDa) and Smo (smoothened 86KDa) of Hh signaling pathway associated with the development of early embryos significantly increased with the increase of irradiation dose. Expression of the AKT (56KDa) and PiK3r3 (55KDa) genes, which are anti-apoptotic and involved with the PI3K/Akt signaling pathway, significantly decreased, while expression of the bada gene, which is pro-apoptotic, significantly increased. The results show that γ-ray irradiations of 0.01 and 0.05Gy can induce developmental toxicity and apoptosis in zebrafish embryos via Hh and PI3K/Akt signaling pathways, respectively.

Stress-Triggered Long-Distance Communication Leads to Phenotypic Plasticity: The Case of the Early Root Protoxylem Maturation Induced by Leaf Wounding in Arabidopsis.

Root architecture and xylem phenotypic plasticity influence crop productivity by affecting water and nutrient uptake, especially under those environmental stress, which limit water supply or imply excessive water losses. Xylem maturation depends on coordinated events of cell wall lignification and developmental programmed cell death (PCD), which could both be triggered by developmental- and/or stress-driven hydrogen peroxide (H2O2) production. Here, the effect of wounding of the cotyledonary leaf on root protoxylem maturation was explored in Arabidopsis thaliana by analysis under Laser Scanning Confocal Microscope (LSCM). Leaf wounding induced early root protoxylem maturation within 3 days from the injury, as after this time protoxylem position was found closer to the tip. The effect of leaf wounding on protoxylem maturation was independent from root growth or meristem size, that did not change after wounding. A strong H2O2 accumulation was detected in root protoxylem 6 h after leaf wounding. Furthermore, the H2O2 trap N,N1-dimethylthiourea (DMTU) reversed wound-induced early protoxylem maturation, confirming the need for H2O2 production in this signaling pathway.

I Spy in the Developing Fly a Multitude of Ways to Die.

Cell proliferation and cell death are two opposing, yet complementary fundamental processes in development. Cell proliferation provides new cells, while developmental programmed cell death adjusts cell numbers and refines structures as an organism grows. Apoptosis is the best-characterized form of programmed cell death; however, there are many other non-apoptotic forms of cell death that occur throughout development. Drosophila is an excellent model for studying these varied forms of cell death given the array of cellular, molecular, and genetic techniques available. In this review, we discuss select examples of apoptotic and non-apoptotic cell death that occur in different tissues and at different stages of Drosophila development. For example, apoptosis occurs throughout the nervous system to achieve an appropriate number of neurons. Elsewhere in the fly, non-apoptotic modes of developmental cell death are employed, such as in the elimination of larval salivary glands and midgut during metamorphosis. These and other examples discussed here demonstrate the versatility of Drosophila as a model organism for elucidating the diverse modes of programmed cell death.

Possibilities and limitations of three-dimensional reconstruction and simulation techniques to identify patterns, rhythms and functions of apoptosis in the early developing neural tube

The now classical idea that programmed cell death (apoptosis) contributes to a plethora of developmental processes still has lost nothing of its impact. It is, therefore, important to establish effective three-dimensional (3D) reconstruction as well as simulation techniques to decipher the exact patterns and functions of such apoptotic events. The present study focuses on the question whether and how apoptosis promotes neurulation-associated processes in the spinal cord of Tupaia belangeri (Tupaiidae, Scandentia, Mammalia). Our 3D reconstructions demonstrate that at least two craniocaudal waves of apoptosis consecutively pass through the dorsal spinal cord. The first wave appears to be involved in neural fold fusion and/or in selection processes among premigratory neural crest cells. The second one seems to assist in establishing the dorsal signaling center known as the roof plate. In the hindbrain, in contrast, apoptosis among premigratory neural crest cells progresses craniocaudally but discontinuously, in a segment-specific manner. Unlike apoptosis in the spinal cord, these segment-specific apoptotic events, however, precede later ones that seemingly support neural fold fusion and/or postfusion remodeling. Arguing with Whitehead that biological patterns and rhythms differ in that biological rhythms depend "upon the differences involved in each exhibition of the pattern" (Whitehead in An enquiry concerning the principles of natural knowledge. Cambridge University Press, London, 1919, p. 198) we show that 3D reconstruction and simulation techniques can contribute to distinguish between (static) patterns and (dynamic) rhythms of apoptosis. By deciphering novel patterns and rhythms of developmental apoptosis, our reconstructions help to reconcile seemingly inconsistent earlier findings in chick and mouse embryos, and to create rules for computer simulations.

NGF, TrkA-P and neuroprotection after a hypoxic event in the developing central nervous system

A decrease in the concentration of oxygen in the blood and tissues (hypoxia) produces important, sometimes irreversible, damages in the central nervous system (CNS) both during development and also postnatally. The present work aims at analyzing the expression of nerve growth factor (NGF) and p75 and the activation of TrkA in response to an acute normobaric hypoxic event and to evaluate the possible protective role of exogenous NGF. The developing chick optic tectum (OT), a recognized model of corticogenesis, was used as experimental system by means of in vivo and in vitro studies.Based on identification of the period of highest sensitivity of developmental programmed cell death (ED15) we show that hypoxia has a mild but reproducible effect that consist of a temporal increase of cell death 6 h after the end of a hypoxic treatment. Cell death was preceded by a significant early increase in the expression of Nerve Growth Factor (NGF) and its membrane receptor p75. In addition, we found a biphasic response of TrkA activation: a decrease during hypoxia followed by an increase −4 h later- that temporally coincide with the interval of NGF overexpression. To test the NGF - NGF receptors role in hypoxic cell death, we quantified, in primary neuronal cultures derived from ED15 OT, the levels of TrkA activation after an acute hypoxic treatment. A significant decline in the level of TrkA activation was observed during hypoxia followed, 24 h later, by significant cell death. Interestingly, this cell death can be reverted if TrkA inactivation during hypoxia is suppressed by the addition of NGF.Our results suggest that TrkA activation may play an important role in the survival of OT neurons subjected to acute hypoxia. The role of TrkA in neuronal survival after injury may be advantageously used for the generation of neuroprotective strategies to improve prenatal insult outcomes.