[Protection effect of recombiant human erythropoietin preconditioning against intrauterine hypoxic-ischemic brain injury and its influence on expression of caspase-3 protein in brain tissue]

OBJECTIVE

To investigate the effects of recombine human erythropoietin (rhEPO) on neural cells apoptosis and the expression of Caspase-3 protein in brain tissue of fetal rats after intrauterine hypoxic-ischemic brain injury.

METHODS

Forty-four Sprague-Dawley rats on 19 days of pregnancy were divided into rhEPO treated group, ischemia-reperfusion group and sham-operated group. Intrauterine hypoxic-ischemic injury of fetal rats was induced by bilateral occlusion of the utero-ovarian artery for 20 min. rhEPO (5000 U/kg) was injected into rats through caudal vein in rhEPO treated group while saline was injected into rats in hypoxic-ischemic group 30 min before hypoxic-ischemic injury. The brain samples in rhEPO treated group and hypoxic-ischemic group were obtained at 30 min, 3 h, 6 h, 24 h and 48 h respectively after artery clamping. There was no hypoxic-ischemic injury in sham-operated group, so the brain samples were obtained at 24 hours after sham operation. Neuroapoptosis in brain tissue was measured by TdT mediated dUTP-biotin nick end labeling (Tunel) staining. The expression of Caspase-3 protein was observed by immunohistochemistry.

RESULTS

The number of apoptosis cells in fetal rat hippocampus after intrauterine hypoxic-ischemic increased progressively with reperfusion. Compared with the I/R group, the number of apoptosis cells decreased in rhEPO treated group (P < 0.01). The expression of Caspase-3 increased rapidly after 3 hours from the reperfusion in the I/R group. Compared with the I/R group, there was less expression of Caspase-3 in rhEPO treated group (P < 0.01).

CONCLUSION

rhEPO showed the effects to inhibit the apoptosis of fetal neural cells and the expression of Caspase-3 protein due to intrauterine hypoxic-ischemic brain injury.

Ontogeny and the effects of in utero brain ischemia on interleukin-1β and interleukin-6 protein expression in ovine cerebral cortex and white matter

Interleukin (IL)-1β and IL-6 have been implicated in brain development, injury progression, and fetal/maternal immune interactions. We examined IL-1β and IL-6 protein expression in cerebral cortex (CC) and white matter (WM) from non-ischemic ovine fetuses at 87-90, 122-127, and 135-137 days of gestation, pregnant ewes at 87-90 and 135-137 days of gestation, and fetuses exposed to 48 or 72h of reperfusion after ischemia. Protein expression was determined by Western immunoblot. In non-ischemic CC, IL-1β was higher (P<0.05) in adult sheep and fetuses at 135-137 than 87-90 and 122-127 days, and IL-6 higher at 122-127 than 87-90 days, and in adults than fetuses at 87-90, 122-127, and 135-137 days of gestation. In non-ischemic fetal WM, IL-6 was higher at 135-137 than 87-90 days, but IL-1β did not differ. In CC, IL-1β was higher in ewes at 135-137 than 87-90 days and IL-6 at 135-137 days and in non-pregnant adults than ewes at 87-90 days of gestation. In WM, IL-1β was higher in ewes at 135-137 than 87-90 days of gestation, but IL-6 did not differ. Forty-eight and 72h after ischemia, CC IL-1β was higher than in non-ischemic fetuses. Seventy-two hours after ischemia, IL-1β and IL-6 were higher in WM than CC. In conclusion, IL-1β and IL-6 exhibit developmental regulation in fetal brain, change during gestation in brains of pregnant ewes, show regional differences in normal brains of fetuses and ewes, demonstrate differential responses after ischemia in CC and WM, and IL-1β but not IL-6 increases after ischemia in CC.

Differential effect of intrauterine hypoxia on caspase 3 and DNA fragmentation in fetal guinea pig hearts and brains

The aim of this study is to quantify the effect of intrauterine hypoxia (HPX) and the role of nitric oxide (NO) on the apoptotic enzyme, caspase 3, and DNA fragmentation in fetal heart and brain. Hypoxia and NO are important regulators of apoptosis, although this has been little studied in the fetal organs. We investigated the effect of intrauterine HPX on apoptosis and the role of NO in both fetal hearts and brains. Pregnant guinea pigs were exposed to room temperature (N = 14) or 10.5% O₂ (N = 12) for 14 days prior to term (term = 65 days) and administered water or L-N6-(1-iminoethyl)-lysine (LNIL), an inducible nitric oxide synthase (iNOS) inhibitor, for 10 days. Fetal hearts and brains were excised from anesthetized near-term fetuses for study. Chronic HPX decreased pro- and active caspase 3, caspase 3 activity, and DNA fragmentation levels in fetal hearts compared with normoxic controls. L-N6-(1-iminoethyl)-lysine prevented the HPX-induced decrease in caspase 3 activity but did not alter DNA fragmentation levels. In contrast, chronic HPX increased both apoptotic indices in fetal brains, which were inhibited by LNIL. Thus, the effect of HPX on apoptosis differs between fetal organs, and NO may play an important role in modulating these effects.

Left-right difference in fetal liver oxygenation during hypoxia estimated by BOLD MRI in a fetal sheep model

OBJECTIVE

The purpose of this study was to measure differences in oxygenation between the left and right sides of the fetal liver during varying oxygenation levels.

METHODS

Eight ewes carrying singleton fetuses at gestational age 125 days (term, 145 days) were included in the study. Under anesthesia the ewes were ventilated with gas containing different levels of oxygen, thereby subjecting the fetuses to hyperoxia (mean ± SD maternal arterial partial pressure of oxygen (pO2), 23.2 ± 8.2 kPa) and hypoxia (mean maternal arterial pO2, 7.1 ± 0.5 kPa). Changes in oxygenation within the fetal liver were assessed by blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI).

RESULTS

During hyperoxia there was no difference between the BOLD signal in the left and right sides of the fetal liver; mean change in BOLD (ΔBOLD)(hyperox), -0.9 ± 3.7%. During hypoxia, however, the decrease in the BOLD signal was more pronounced in the right side as compared with the left side, thereby creating a significant increase in the left-right difference in the BOLD signal; mean ΔBOLD(hypox), 5.2 ± 2.2% (P = 0.002, paired t-test). The left-right difference was directly proportional to the degree of hypoxia (R2 = 0.86, P = 0.007).

CONCLUSIONS

To our knowledge, this is the first study demonstrating differences in oxygenation between the left and right sides of the fetal liver during hypoxia, a difference that can be explained by increased ductus venosus shunting. Thus, the BOLD MRI technique is a promising non-invasive tool that might be useful for the future monitoring of the human fetus.

[Biochemical aspects of fetal hypoxia]

OBJECTIVE

To evaluate validity of biochemical diagnostic methods of fetal hypoxia.

DESIGN

A case-control study.

SETTING

Department of Gynecology and Obstetrics, Jessenius Faculty of Medicine, Comenius University, Martin, Slovak Republic.

METHODS

We included 67 patients, and they were retrospectively divided into group of controls (n=36), and studied group (n=31) according to pH in umbilical artery (UA) <7.15. Acid-base parameters were assessed with Rapidlab 248, Bayer Healthcare LLC, East Walpole, USA. We determined criterion for metabolic acidosis (MAC) as pH UA <7.15, resp. base deficit (BD) UA >12 mmol/l. Postpartal lactate concentration in umbilical vein (UV) and UA was determined with lactatemeter Accutrend Lactate, Roche Diagnostics, Switzerland. Quantitative assessment of fetal human protein S100B was provided with ELISA (Sangtec 100 ELISA, DiaSorin Inc., Stillwater, Minnesota, USA). Fetal erythropoietin concentration in UV was examined with immunoenzymatic assessment Access EPO (Beckman Coulter, Inc., Fullerton, CA, USA).

STATISTICS

histograms, Kolmogorov-Smirnov test, Mann-Whitney test, Spearman's rho; statistical significance: p<0.05, Receiver Operating Characteristic curves, Area Under the Curve.

RESULTS

The best correlation was between fetal acid-base parameters and lactate in UA (p<0.0005). Significant correlation was between EPO in UV, and protein S100B in UV (p<0.05). EPO in UV significantly correlated with lactate in UA (p<0.05). Correlation between EPO in UV and protein S100B was not significant. According to ROC curves in prediction of fetal hypoxia, we found an excellent accuracy (AUC>0.9) for lactate in UA, good accuracy (AUC>0.7) had EPO in UV. Results for protein S100B were not significant. The highest sensitivity had EPO in UV, while the highest specificity has had lactate in UA.

CONCLUSION

An indisputable evidence of labor management quality is the fetal metabolic status. On the basis of our results, the suitable clinical markers are lactate and EPO, in addition to acid-base parameters.

Humans at high altitude: hypoxia and fetal growth

High-altitude studies offer insight into the evolutionary processes and physiological mechanisms affecting the early phases of the human lifespan. Chronic hypoxia slows fetal growth and reduces the pregnancy-associated rise in uterine artery (UA) blood flow. Multigenerational vs. shorter-term high-altitude residents are protected from the altitude-associated reductions in UA flow and fetal growth. Presently unknown is whether this fetal-growth protection is due to the greater delivery or metabolism of oxygen, glucose or other substrates or to other considerations such as mechanical factors protecting fragile fetal villi, the creation of a reserve protecting against ischemia/reperfusion injury, or improved placental O(2) transfer as the result of narrowing the A-V O(2) difference and raising uterine P(v)O₂. Placental growth and development appear to be normal or modified at high altitude in ways likely to benefit diffusion. Much remains to be learned concerning the effects of chronic hypoxia on embryonic development. Further research is required for identifying the fetoplacental and maternal mechanisms responsible for transforming the maternal vasculature and regulating UA blood flow and fetal growth. Genomic as well as epigenetic studies are opening new avenues of investigation that can yield insights into the basic pathways and evolutionary processes involved.

Application of comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry method to identify potential biomarkers of perinatal asphyxia in a non-human primate model

Perinatal asphyxia is a leading cause of brain injury in infants, occurring in 2-4 per 1000 live births. The clinical response to asphyxia is variable and difficult to predict with current diagnostic tests. Reliable biomarkers are needed to help predict the timing and severity of asphyxia, as well as response to treatment. Two-dimensional gas chromatography-time-of-flight-mass spectrometry (GC×GC-TOFMS) was used herein, in conjunction with chemometric data analysis approaches for metabolomic analysis in order to identify significant metabolites affected by birth asphyxia. Blood was drawn before and after 15 or 18 min of cord occlusion in a Macaca nemestrina model of perinatal asphyxia. Postnatal samples were drawn at 5 min of age (n=20 subjects). Metabolomic profiles of asphyxiated animals were compared to four controls delivered at comparable gestational age. Fifty metabolites with the greatest change pre- to post-asphyxia were identified and quantified. The metabolic profile of post-asphyxia samples showed marked variability compared to the pre-asphyxia samples. Fifteen of the 50 metabolites showed significant elevation in response to asphyxia, ten of which remained significant upon comparison to the control animals. This metabolomic analysis confirmed lactate and creatinine as markers of asphyxia and discovered new metabolites including succinic acid and malate (intermediates in the Krebs cycle) and arachidonic acid (a brain fatty acid and inflammatory marker) as potential biomarkers. GC×GC-TOFMS coupled with chemometric data analysis are useful tools to identify acute biomarkers of brain injury. Further study is needed to correlate these metabolites with severity of disease, and response to treatment.

Nitric oxide inhibits ACTH-induced cortisol production in near-term, long-term hypoxic ovine fetal adrenocortical cells

We previously reported that in the sheep fetus, long-term hypoxia (LTH) resulted in elevated basal plasma adrenocorticotropic hormone (ACTH(1- 39)) whereas the cortisol levels were not different from normoxic controls. We also showed that LTH enhances endothelial nitric oxide synthase (eNOS) expression in the fetal adrenal. This study was designed to determine the effect of NO on cortisol production in adrenocortical cells from LTH fetal sheep. Ewes were maintained at high altitude (3820 m) from ∼40 days' gestation (dG) to near term. Between 138 and 141 dG, fetal adrenal glands were collected from LTH and age-matched normoxic control fetuses. Adrenal cortical cells were pretreated with sodium nitroprusside (SNP), nitro-L-arginine methyl ester (L-NAME), L-arginine, or diethyleneamine NO (DETA-NO) and then challenged with 10 nmol/L ACTH. Cortisol responses were compared after 1 hour. Adrenocorticotropic hormone -induced cortisol secretion was significantly higher in LTH versus control (P < .01). Enhancement of NO with L-arginine resulted in a significant reduction of ACTH-mediated cortisol production in the LTH group. DETA-NO also caused a significant decrease in ACTH-mediated cortisol production (P < .05). Inhibition of NOS with L-NAME significantly increased cortisol production in the LTH group (P < .05 compared to ACTH alone), whereas the effect on the control group was not significant. Nitric oxide synthase activity was significantly higher in the LTH group compared to control, but this difference was eliminated following ACTH treatment. These data indicate that LTH enhances adrenal cortical sensitivity to the inhibitory effects of NO on cortisol production. Nitric oxide may, therefore, play an important role in regulating ACTH-induced cortisol production in the LTH fetal adrenal.

Non-invasive detection and quantification of human foetal brain lactate in utero by magnetic resonance spectroscopy

OBJECTIVE

To assess the feasibility of foetal cerebral lactate detection and quantification by proton magnetic resonance spectroscopy ((1)H-MRS) in pregnancies at increased risk of cerebral hypoxia, using a clinical 1.5 T magnetic resonance imaging (MRI) system.

METHOD

Localised (1)H-MRS was performed in four patients with pregnancies in their third trimester complicated by intrauterine growth restriction (IUGR). A long echo time (TE) of 288 ms was used to maximise detection and conspicuity of the lactate methyl resonance, together with a short TE MRS acquisition to check for the presence of lipid contamination. Individual peaks in the resulting spectra were measured, corrected for relaxation and referenced to the unsuppressed water signal to provide metabolite concentrations.

RESULTS

A resonance peak consistent with the presence of lactate was observed in all cases. In one subject, this was confounded by the identification of significant lipid contamination in the short TE MRS acquisition. The range of measured lactate concentrations was 2.0-3.3 mmol/kg and compared well with preterm neonatal MRS studies.

CONCLUSION

The non-invasive detection and quantification of foetal cerebral lactate by MRS is achievable on a clinical 1.5 T MRI system.

The effects of hypoxia on growth cones in the ovine fetal brain

OBJECTIVE

This study was designed to investigate the effects of hypoxia on neural process proliferation by studying its effects on growth cone tubulin and insulin-like growth factor (IGF)-I receptor content.

METHODS

Six fetal lambs were catheterized in the brachial artery and vein. Maternal oxygenation was reduced in steps from a fractional inspired oxygen concentration (FiO2) of 20% to 6% by addition of nitrogen to the inhaled gas mixture for a period of 4 h of reduced oxygen intake. Fetal arterial blood was sampled after the maternal FiO2 and oxygen were stable for >5 min at maternal FiO2 of 20% to 6%. Controls were obtained from normoxic fetuses whose ewes had similar surgery and were kept at an FiO2 of 20% throughout the experiment. Growth cones were isolated from the fetal cerebrum and cerebellum. alpha-tubulin and IGF-I receptors were quantified by immunoblotting. Tubulin and IGF-I receptor mRNA expressions were quantified by real-time polymerase chain reaction.

RESULTS

Maternal nitrogen breathing reduced fetal arterial pH from 7.32+/-0.06 to 6.99+/-0.02 (p<0.001). Hypoxia increased IGF-I receptors from 143+/-10 to 327+/-14 (p<0.001) and from 272+/-26 to 396+/-34 (p<0.001) fluorescence units/microg protein in the cerebrum and cerebellum, respectively. It also increased alpha-tubulin from 713+/-30 to 1873+/-126 (p<0.001) and from 780+/-34 to 2362+/-79 (p<0.001) fluorescence units/microg protein in the cerebrum and cerebellum, respectively. Expression of IGF-I receptor mRNA increased significantly in the hypoxic animals both in the cerebrum and the cerebellum, but there was no change in expression of alpha-tubulin mRNA.

CONCLUSIONS

This increase in IGF-I receptor expression and growth cone content may be an adaptive response to hypoxia to maintain neurite growth by facilitating binding of IGF-I. Hypoxia also increased the growth cone level of alpha-tubulin but did not increase its mRNA expression, which may indicate an inability to polymerize tubulin and build microtubules.

[Permeability of exogenetic recombine human erythropoietin through placenta barrier to fetal rats with transient uteroplacental ischemia]

OBJECTIVE

To investigate whether recombine human erythropoietin can cross the placenta barrier in rats with transient uteroplacental ischemia.

METHODS

Rats on day 19 of pregnancy were divided into ischemia-reperfusion group, sham-operated group and rhEPO treated group. Fetal ischemia was induced by bilateral occlusion of the utero-ovarian artery for 20 minutes. 125I-rhEPO or saline were administered intravenously 30 min before the induction of hypoxic-ischemic injury. Fetal rat organs were removed to measure the radioactivity post injury.

RESULTS

A small amount of radioactive activity (1.26 +/- 0.28) pg/g was detected in the fetal rats with ischemia-reperfusion. 125I-rhEPO radioactivity increased gradually with time in the placenta, amniotic fluid and fetal tissues of vital organs in the rats of sham-operated group and rhEPO treatment group. There were significant differences in 125I-rhEPO between placental organs and other organs (P < 0.05). The permeability of 125I-rhEPO through the blood brain barrier changed with reperfusion time and peaked about 6 h after reperfusion, and significant differences were found between rhEPO treatment group and sham operation group (P < 0.05).

CONCLUSION

Exogenous rhEPO can cross the placenta barrier and blood-brain barrier and reach hypoxic-ischemic fetal rats.

[Dopamine D4 receptor hypoxia sensitivity and child psychiatric disorders]

Attention-deficit hyperactivity disorder (ADHD) is one of the most frequent child psychiatric problems with a complex genetic and environmental background. According to the prevailing view, main factors of the disorder are prefrontal dopamine deficiency and incomplete central dopaminergic functioning. Twin studies suggest substantial heritability in the background of the disease, and the studied candidate genes involve components of the dopamine system. Moreover, various noxious pre- and perinatal environmental impacts have been implicated in the pathogenesis of ADHD. Here we review experimental results from epidemiological, tissue and animal studies that assigned a causal role to fetal hypoxia in the development of ADHD and pointed out that the dopaminergic neurotransmission is sensitive to hypoxia. Allelic variants of the D4 dopamine receptor (DRD4) are well characterized risk factors of ADHD. Recently we have reported that hypoxia enhanced the promoter activity of DRD4 gene several fold. These observations suggest that the effect of hypoxia on the dopaminergic neurotransmission might be an important factor in the pathomechanism of ADHD.

The relation of S100beta and metabolic and endocrine responses to acute fetal hypoxemia

Elevations in S100beta protein in umbilical cord blood have been proposed as a reproducible marker of fetal stress, leading to cell damage within the central nervous system. However, it remains unknown whether fetal S100beta concentrations correlate with established endocrine and metabolic indices of fetal distress. Hence, in the late gestation ovine fetus, plasma concentrations of S100beta, adrenocorticotropic hormone (ACTH), cortisol, neuropeptide Y (NPY), and catecholamines and blood concentrations of glucose and lactate were measured during acute hypoxemia. Under general anesthesia, 5 sheep fetuses were chronically instrumented with catheters and subjected 5 days later to 1h normoxia, 0.5h hypoxemia and 1h recovery. Plasma samples were taken during each experimental period. Hypoxemia induced significant falls in PaO2 with increases in fetal plasma concentrations of ACTH, cortisol, catecholamines and NPY, and elevations in blood glucose and lactate, all of which showed significant positive relationships with fetal plasma S100beta concentrations. Hence, evaluation of S100beta may provide a valuable clinical tool in the assessment of fetal well-being in suspected complicated pregnancies.

[Effect of intrauterine hypoxia upon newborn albino rat tooth germ cells anabolic activity]

The aim of this study was to examine the intrauterine hypoxia influence on dental hard tissue development. Pregnant rats were exposed in hypoxic environments between day 14 and 19 of pregnancy. The study was performed on 36 newborn albino rats. Analysis of nucleolar organizator parameters were performed in enameloblasts, odontoblasts and saliva gland epitheliocytes. Data obtained demonstrated that intrauterine hypoxia decreased nucleolar organizator quantity in enameloblasts of tooth germ.

Maturation and long-term hypoxia alters Ca2+-induced Ca2+ release in sheep cerebrovascular sympathetic neurons

The contribution of sympathetic nerves arising from the superior cervical ganglia (SCG) toward the growth and function of cerebral blood vessels is pertinent throughout maturation as well as in response to cardiovascular stress imposed by high-altitude long-term hypoxia (LTH). The function of SCG sympathetic neurons is dependent on intracellular Ca2+ concentration ([Ca2+]i) signaling, which is strongly influenced by a process known as Ca(2+)-induced Ca2+ release (CICR) from the smooth endoplasmic reticulum (SER). In this study, we used the sheep SCG neuronal model to test the hypotheses that maturation decreases CICR and high-altitude LTH depresses CICR in fetal SCG neurons but not in those of the adult. We found that the contribution of CICR to electric field stimulation (EFS)-evoked [Ca2+]i transients was greatest in SCG cells from normoxic fetuses and was abolished by LTH. The decline in CICR was associated with a reduction in sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) function in fetal SCG cells during LTH, reducing SER Ca2+ levels below the threshold needed for the coupling of Ca2+ influx and CICR. With respect to the maturation from the fetus to adult, the decrease in CICR may reflect both a reduction in the levels of ryanodine receptor isoforms 2 and 3 and SERCA function. In response to LTH and in contrast to the fetus, CICR function in adult SCG cells is maintained and may reflect alterations in other mechanisms that modulate the CICR process. As CICR is instrumental in the function of sympathetic neurons within the cerebrovasculature, the loss of this signaling mechanism in the fetus may have consequences for the adaptation to LTH in terms of fetal susceptibility to vascular insults.

Tetrahydrobiopterin in the prevention of hypertonia in hypoxic fetal brain

OBJECTIVE

Tetrahydrobiopterin (BH(4)) deficiency is a cause of dystonia at birth. We hypothesized that BH(4) is a developmental factor determining vulnerability of the immature fetal brain to hypoxic-ischemic injury and subsequent motor deficits in newborns.

METHODS

Pregnant rabbits were subjected to 40-minute uterine ischemia, and fetal brains were investigated for global and focal changes in BH(4). Newborn kits were assessed by neurobehavioral tests following vehicle and sepiapterin (BH(4) analog) treatment of dams.

RESULTS

Naive fetal brains at 70% gestation (E22) were severely deficient for BH(4) compared with maternal and other fetal tissues. BH(4) concentration rapidly increased normally in the perinatal period, with the highest concentrations found in the thalamus compared with basal ganglia, frontal, occipital, hippocampus, and parietal cortex. Global sustained 40-minute hypoxia-ischemia depleted BH(4) in E22 thalamus and to a lesser extent in basal ganglia, but not in the frontal, occipital, and parietal regions. Maternal supplementation prior to hypoxia-ischemia with sepiapterin increased BH(4) in all brain regions and especially in the thalamus, but did not increase the intermediary metabolite, 7,8-BH(2). Sepiapterin treatment also reduced incidence of severe motor deficits and perinatal death following E22 hypoxia-ischemia.

INTERPRETATION

We conclude that early developmental BH(4) deficiency plays a critical role in hypoxic-ischemic brain injury. Increasing brain BH(4) via maternal supplementation may be an effective strategy in preventing motor deficits from antenatal hypoxia-ischemia.

MCI-186 administered to the maternal circulation inhibits fetal brain injury resulting from total umbilical cord occlusion in the chronically instrumented fetal lamb

OBJECTIVE

To evaluate the transplacental effects of MCI-186 (edaravone), a potent hydroxyl radical scavenger, administered to the maternal circulation to inhibit fetal brain injury caused by umbilical cord occlusion.

METHODS

Nine chronically instrumented lambs were prepared. In three cases, 10-min persistent total umbilical cord occlusion (group A) was performed. Another three cases underwent occlusion and were administered 60 mg of MCI-186 through the maternal femoral vein prior to the end of occlusion (group B). The remaining three cases underwent sham operation (group C). On day 3 after insult, fetal brains were extirpated. Paraffin-embedded brain tissue sections were stained with hematoxylin and eosin, Bodian, Kluver-Barrera, and TUNEL. Neuronal cellular damage was evaluated by two pathologists blinded to the experimental conditions.

RESULTS

Group A displayed numerous cells with eosinophilic condensation of nuclear chromatin and proliferation of microglia in the hippocampus and basal ganglia. TUNEL-positive cells were observed in the periventricular area. Group B showed microglial proliferations, but no marked changes. No pathological changes were apparent in group C.

CONCLUSIONS

MCI-186 administered to the maternal circulation could inhibit fetal brain injury resulting from hypoxia-reperfusion induced by umbilical cord occlusion.

Changes in beta(1) integrin in renal tubular epithelial cells after intrauterine asphyxia of rabbit pups

OBJECTIVE

We investigated the role of beta(1) integrin in acute renal tubular injury caused by intrauterine asphyxia of neonatal rabbits by exploring the distribution and expression changes in beta(1) integrin and its mRNA in renal tubular epithelial cells.

METHODS

A catheter was used to temporarily block the abdominal aortas of New Zealand pregnant rabbits in order to set up the intrauterine asphyxia animal model. The rabbit pups were randomly divided into control, asphyxia, and calpain inhibitor intervention groups and their renal tubular tissues were examined at 2 h after asphyxia. Immunofluorescence and in situ hybridization were used to examine the expression of beta(1) integrin and its mRNA, respectively. Western blot analysis was used to show the proteolysis of beta(1) integrin. Calpain inhibitor I was used to show the protective effect of keeping beta(1) integrin from being hydrolyzed after asphyxia.

RESULTS

(1) Normally, beta(1) integrin was located exclusively at the basal surface of renal tubular epithelial cells. After asphyxia a large amount of beta(1) integrin shifted from the basal surface to the cytoplasma and the lateral and apical surfaces and its expression decreased significantly, with simultaneous damage to renal tubular integrity and structure, many exfoliated cells and cell fragments obstructed the tubular lumen. (2) The mRNA of beta(1) integrin was mainly expressed in the cytoplasma. After asphyxia its expression increased significantly. (3) Proteolysis of beta(1) integrin was evident after asphyxia, but was significantly reduced in the calpain inhibitor intervention group. Calpain inhibitor I prevented the decrease and dislocation of beta(1) integrin and protected renal tubular integrity and structure.

CONCLUSION

Intrauterine asphyxia caused proteolysis of beta(1) integrin, with reduced expression and depolarized distribution, leading to tubular lumen obstruction and renal tubule destruction. Damage to beta(1) integrin and the renal tubule was related to the activation of calpain, and calpain inhibitor curtailed these effects.

Amniotic fluid S100B protein and erythropoietin in pregnancies at risk for fetal hypoxia

OBJECTIVE

S100B protein is a biochemical marker for brain injury, and high serum S100B levels have been observed in newborns with birth asphyxia. We hypothesized that the concentration of amniotic fluid erythropoietin, which increases in chronic fetal hypoxia, correlates with amniotic fluid S100B concentration.

STUDY DESIGN

Amniotic fluid samples in 35 pregnancies at high risk for chronic fetal hypoxia were obtained at cesarean section or by amniocentesis done within a median of 2 days before delivery. S100B and erythropoietin concentrations were measured by chemiluminescent immunoassays.

RESULTS

A positive correlation existed between the concentrations of S100B and erythropoietin in the amniotic fluid (r=0.57, p<0.0001). Amniotic fluid S100B concentration was higher (70 ng/l; 33-469, n=17) (median; range) in pregnancies with elevated amniotic fluid erythropoietin (>or= 50 IU/l) than in pregnancies with normal erythropoietin (34 ng/l; 20-340, n=18) (p<0.0001, Mann-Whitney U-test). S100B predicted an elevated amniotic fluid erythropoietin concentration in the study population with the sensitivity of 94% and specificity of 83%.

CONCLUSION

A strong positive correlation exists between amniotic fluid S100B and erythropoietin concentrations in pregnancies at high risk for chronic fetal hypoxia. This suggests that chronic fetal hypoxia increases the intrauterine release of S100B.

Nitric oxide synthesis in placenta is increased in intrauterine growth restriction and fetal hypoxia

In order to study the possible role of nitric oxide (NO) in the human placenta, we measured the concentration of its stable metabolite nitrite (NO2-) in the placentas of women with normal pregnancies and those from pregnancies complicated by intrauterine growth restriction (IUGR) with or without fetal hypoxia. We have measured nitrites by the Griess reaction in 15 placentas from IUGR pregnancies and 12 controls. Cerebroumbilical ratio (C:U) was recorded by color Doppler ultrasound and values below 1 were considered to be a predictor for fetal hypoxia. NO2- levels measured in pathological placentas were increased for at least 93% as compared to control. Subjects from pregnancies complicated by IUGR and fetal hypoxia had increased NO2- as compared to the placentas from pregnancies with IUGR and normal fetal oxygenation. NO production in placenta is increased in pregnancies with IUGR. This effect is more pronounced in those with compromised fetal oxygenation.

Maternal creatine: does it reach the fetus and improve survival after an acute hypoxic episode in the spiny mouse (Acomys cahirinus)?

OBJECTIVE

We hypothesized that elevating creatine in the maternal diet would reach fetal and placental tissues and improve fetal survival after acute hypoxia at birth.

STUDY DESIGN

Pregnant spiny mice were fed a control or 5% creatine-supplemented diet from day 20 of gestation (term, approximately 39 days). On days 37-38, intrauterine hypoxia was induced by placement of the isolated uterus in a saline solution bath for 7.5-8 minutes, after which fetuses were expelled from the uterus and resuscitation was attempted by manual palpation of the chest. Total creatine content (creatine + phosphocreatine) of placental, fetal, and maternal organs was measured.

RESULTS

The maternal creatine diet significantly increased total creatine content in the placenta, fetal brain, heart, liver, and kidney and increased the capacity of offspring to survive birth hypoxia. Maternal creatine improved postnatal growth after birth hypoxia.

CONCLUSION

This study provides evidence that creatine has potential as a prophylactic therapy for pregnancies that are classified as high risk for fetal hypoxia.

Neurosteroids in the fetus and neonate: Potential protective role in compromised pregnancies

Complications during pregnancy and birth asphyxia lead to brain injury, with devastating consequences for the neonate. In this paper we present evidence that the steroid environment during pregnancy and at birth aids in protecting the fetus and neonate from asphyxia-induced injury. Earlier studies show that the placental progesterone production has a role in the synthesis and release of neuroactive steroids or their precursors into the fetal circulation. Placental precursor support leads to remarkably high concentrations of allopregnanolone in the fetal brain and to a dramatic decline with the loss of the placenta at birth. These elevated concentrations influence the distinct behavioral states displayed by the late gestation fetus and exert a suppressive effect that maintains sleep-like behavioral states that are present for much of fetal life. This suppression reduces CNS excitability and suppresses excitotoxicity. With the availability of adequate precursors, mechanisms within the fetal brain ultimately control neurosteroid levels. These mechanisms respond to episodes of acute hypoxia by increasing expression of 5alpha-reductase and P450scc enzymes and allopregnanolone synthesis in the brain. This allopregnanolone response, and potentially that of other neurosteroids including 5alpha-tetrahydrodeoxycorticosterone (TH-DOC), reduces hippocampal cell death following acute asphyxia and suggests that stimulation of neurosteroid production may protect the fetal brain. Importantly, inhibition of neurosteroid synthesis in the fetal brain increases the basal cell death suggesting a role in controlling developmental processes late in gestation. Synthesis of neurosteroid precursors in the fetal adrenal such as deoxycorticosterone (DOC), and their conversion to active neurosteroids in the fetal brain may also have a role in neuroprotection. This suggests that the adrenal glands provide precursor DOC for neurosteroid synthesis after birth and this may lead to a switch from allopregnanolone alone to neuroprotection mediated by allopregnanolone and TH-DOC.

Chronic hypoxia differentially increases glutathione content and gamma-glutamyl cysteine synthetase expression in fetal guinea pig organs

OBJECTIVE

Glutathione is a natural antioxidant in the fetus and adult. We sought to determine whether maternal hypoxia alters glutathione levels in fetal organs as an adaptive response to the reduced oxygenation.

STUDY DESIGN

Timed pregnant guinea pigs were housed in either a Plexiglas chamber containing 10.5% O(2) from 46 to 60 days gestation (HPX, n=6) or in room air, as the normoxic control (NMX, n=5). Pregnant guinea pigs were anesthetized at near term ( approximately 60 days, term=65 days) and liver, lungand kidney were excised from anesthetized fetuses and stored frozen (-80 degrees C) prior to sample processing. Using the hypoxia marker, pimonidazole, we measured a hypoxia-induced increase in stained cells of fetal liver compared to no change in either the lung or kidney. To measure the effect of hypoxia among different organs, total glutathione (GSH) content and protein levels of gamma-glutamyl cysteine synthetase (gamma-GCS) were measured from the same organs.

RESULTS

Maternal hypoxia increased (P<0.05) total glutathione levels by 121% in the fetal liver but had no effect in either fetal lung or kidney. Chronic hypoxia increased (P<0.05) gamma-GCS protein levels in all three fetal organs studied.

CONCLUSION

These results demonstrate that the fetal response to maternal hypoxia may be organ specific. The increase in fetal liver glutathione via upregulation of gamma-GCS may be an important adaptive response to prolonged hypoxic stress.