Maternal Allopurinol Prevents Cardiac Dysfunction in Adult Male Offspring Programmed by Chronic Hypoxia During Pregnancy

Integrating functional and molecular levels, we investigated the effects of maternal treatment with a xanthine oxidase inhibitor on the programming of cardiac dysfunction in adult offspring using an established rat model of hypoxic pregnancy. Female Wistar rats were divided into normoxic or hypoxic (13% O₂) pregnancy±maternal allopurinol treatment (30 mg kg^-1 d^-1). At 4 months, hearts were isolated from 1 male per litter per outcome variable to determine cardiac function and responses to ischemia-reperfusion in a Langendorff preparation. Sympathetic dominance, perfusate CK (creatine kinase) and LDH (lactate dehydrogenase) and the cardiac protein expression of the β₁-adrenergic receptor, the M₂ Ach receptor (muscarinic type-2 acetylcholine receptor), and the SERCA2a (sarcoplasmic reticulum Ca²⁺ ATPase 2a) were determined. Relative to controls, offspring from hypoxic pregnancy showed elevated left ventricular end diastolic pressure (+34.7%), enhanced contractility (dP/dt_max, +41.6%), reduced coronary flow rate (-21%) and an impaired recovery to ischemia-reperfusion (left ventricular diastolic pressure, area under the curve recovery -19.1%; all P<0.05). Increased sympathetic reactivity (heart rate, +755.5%; left ventricular diastolic pressure, +418.9%) contributed to the enhanced myocardial contractility ( P<0.05). Perfusate CK (+431%) and LDH (+251.3%) and the cardiac expression of SERCA2a (+71.4%) were also elevated ( P<0.05), further linking molecular markers of cardiac stress and injury to dysfunction. Maternal allopurinol restored all functional and molecular indices of cardiac pathology. The data support a link between xanthine oxidase-derived oxidative stress in hypoxic pregnancy and cardiac dysfunction in the adult offspring, providing a target for early intervention in the developmental programming of heart disease.

Behavioral and neurodevelopmental outcome of children after maternal allopurinol administration during suspected fetal hypoxia: 5-year follow up of the ALLO-trial

OBJECTIVE

To evaluate the long-term neurodevelopmental and behavioral outcome of antenatal allopurinol treatment during suspected fetal hypoxia.

STUDY DESIGN

We studied children born from women who participated in a randomized double-blind placebo controlled multicenter study (ALLO-trial). Labouring women in whom the fetus was suspected to have fetal hypoxia were randomly allocated to receive allopurinol or placebo. At 5 years of age, the children were assessed with 2 parent reported questionnaires, the Ages and Stages Questionnaire (ASQ) and the Child Behavior Checklist (CBCL). A child was marked abnormal for ASQ if it scored below 2 standard deviation under the normative mean of a reference population in at least one domain. For CBCL, a score above the cut-off value (95th percentile for narrowband scale, 85th percentile for broadband scale) in at least one scale was marked as abnormal.

RESULTS

We obtained data from 138 out of the original 222 mildly asphyxiated children included in the ALLO-trial (response rate 62%, allopurinol n = 73, placebo n = 65). At 5 years of age, the number of children that scored abnormal on the ASQ were 11 (15.1%) in the allopurinol group versus 11 (9.2%) in the placebo group (relative risk (RR) 1.64, 95% confidence interval (CI): 0.64 to 4.17, p = 0.30). On CBCL 21 children (30.4%) scored abnormal in de allopurinol group versus 12 children (20.0%) in the placebo group (RR 1.52, 95% CI: 0.82 to 2.83, p = 0.18).

CONCLUSION

We found no proof that allopurinol administered to labouring women with suspected fetal hypoxia improved long-term developmental and behavioral outcome. These findings are limited due to the fact that the study was potentially underpowered.

TRIAL REGISTRATION

NCT00189007 Dutch Trial Register NTR1383.

Divergence of mechanistic pathways mediating cardiovascular aging and developmental programming of cardiovascular disease

Aging and developmental programming are both associated with oxidative stress and endothelial dysfunction, suggesting common mechanistic origins. However, their interrelationship has been little explored. In a rodent model of programmed cardiovascular dysfunction we determined endothelial function and vascular telomere length in young (4 mo) and aged (15 mo) adult offspring of normoxic or hypoxic pregnancy with or without maternal antioxidant treatment. We show loss of endothelial function [maximal arterial relaxation to acetylcholine (71 ± 3 vs. 55 ± 3%) and increased vascular short telomere abundance (4.2–1.3 kb) 43.0 ± 1.5 vs. 55.1 ± 3.8%) in aged vs. young offspring of normoxic pregnancy (P < 0.05). Hypoxic pregnancy in young offspring accelerated endothelial dysfunction (maximal arterial relaxation to acetylcholine: 42 ± 1%, P < 0.05) but this was dissociated from increased vascular short telomere length abundance. Maternal allopurinol rescued maximal arterial relaxation to acetylcholine in aged offspring of normoxic or hypoxic pregnancy but not in young offspring of hypoxic pregnancy. Aged offspring of hypoxic allopurinol pregnancy compared with aged offspring of untreated hypoxic pregnancy had lower levels of short telomeres (vascular short telomere length abundance 35.1 ± 2.5 vs. 48.2 ± 2.6%) and of plasma proinflammatory chemokine (24.6 ± 2.8 vs. 36.8 ± 5.5 pg/ml, P < 0.05). These data provide evidence for divergence of mechanistic pathways mediating cardiovascular aging and developmental programming of cardiovascular disease, and aging being decelerated by antioxidants even prior to birth.—Allison, B. J., Kaandorp, J. J., Kane, A. D., Camm, E. J., Lusby, C., Cross, C. M., Nevin-Dolan, R., Thakor, A. S., Derks, J. B., Tarry-Adkins, J. L., Ozanne, S. E., Giussani, D. A. Divergence of mechanistic pathways mediating cardiovascular aging and developmental programming of cardiovascular disease.

Maternal allopurinol administration during suspected fetal hypoxia: a novel neuroprotective intervention? A multicentre randomised placebo controlled trial

OBJECTIVE

To determine whether maternal allopurinol treatment during suspected fetal hypoxia would reduce the release of biomarkers associated with neonatal brain damage.

DESIGN

A randomised double-blind placebo controlled multicentre trial.

PATIENTS

We studied women in labour at term with clinical indices of fetal hypoxia, prompting immediate delivery.

SETTING

Delivery rooms of 11 Dutch hospitals.

INTERVENTION

When immediate delivery was foreseen based on suspected fetal hypoxia, women were allocated to receive allopurinol 500 mg intravenous (ALLO) or placebo intravenous (CONT).

MAIN OUTCOME MEASURES

Primary endpoint was the difference in cord S100ß, a tissue-specific biomarker for brain damage.

RESULTS

222 women were randomised to receive allopurinol (ALLO, n=111) or placebo (CONT, n=111). Cord S100ß was not significantly different between the two groups: 44.5 pg/mL (IQR 20.2-71.4) in the ALLO group versus 54.9 pg/mL (IQR 26.8-94.7) in the CONT group (difference in median -7.69 (95% CI -24.9 to 9.52)). Post hoc subgroup analysis showed a potential treatment effect of allopurinol on the proportion of infants with a cord S100ß value above the 75th percentile in girls (ALLO n=5 (12%) vs CONT n=10 (31%); risk ratio (RR) 0.37 (95% CI 0.14 to 0.99)) but not in boys (ALLO n=18 (32%) vs CONT n=15 (25%); RR 1.4 (95% CI 0.84 to 2.3)). Also, cord neuroketal levels were significantly lower in girls treated with allopurinol as compared with placebo treated girls: 18.0 pg/mL (95% CI 12.1 to 26.9) in the ALLO group versus 32.2 pg/mL (95% CI 22.7 to 45.7) in the CONT group (geometric mean difference -16.4 (95% CI -24.6 to -1.64)).

CONCLUSIONS

Maternal treatment with allopurinol during fetal hypoxia did not significantly lower neuronal damage markers in cord blood. Post hoc analysis revealed a potential beneficial treatment effect in girls.

TRIAL REGISTRATION NUMBER

NCT00189007, Dutch Trial Register NTR1383.

Rapid target allopurinol concentrations in the hypoxic fetus after maternal administration during labour

OBJECTIVE

Perinatal hypoxia-induced free radical formation is an important cause of hypoxic-ischaemic encephalopathy and subsequent neurodevelopmental disabilities. Allopurinol reduces the formation of free radicals, which potentially limits hypoxia-induced brain damage. We investigated placental transfer and safety of allopurinol after maternal allopurinol treatment during labour to evaluate its potential role as a neuroprotective agent in suspected fetal hypoxia.

DESIGN

We used data from a randomised, double-blind multicentre trial comparing maternal allopurinol versus placebo in case of imminent fetal hypoxia (NCT00189007).

PATIENTS

We studied 58 women in labour at term, with suspected fetal hypoxia prompting immediate delivery, in the intervention arm of the study.

SETTING

Delivery rooms of 11 Dutch hospitals.

INTERVENTION

500 mg allopurinol, intravenously to the mother, immediately prior to delivery.

MAIN OUTCOME MEASURES

Drug disposition (maternal plasma concentrations, cord blood concentrations) and drug safety (maternal and fetal adverse events).

RESULTS

Within 5 min after the end of maternal allopurinol infusion, target plasma concentrations of allopurinol of ≥2 mg/L were present in cord blood. Of all analysed cord blood samples, 95% (52/55) had a target allopurinol plasma concentration at the moment of delivery. No adverse events were observed in the neonates. Two mothers had a red and/or painful arm during infusion.

CONCLUSIONS

A dose of 500 mg intravenous allopurinol rapidly crosses the placenta and provides target concentrations in 95% of the fetuses at the moment of delivery, which makes it potentially useful as a neuroprotective agent in perinatology with very little side effects.

TRIAL REGISTRATION

The study is registered in the Dutch Trial Register (NTR1383) and the Clinical Trials protocol registration system (NCT00189007).

Xanthine oxidase and the fetal cardiovascular defence to hypoxia in late gestation ovine pregnancy

Hypoxia is a common challenge to the fetus, promoting a physiological defence to redistribute blood flow towards the brain and away from peripheral circulations. During acute hypoxia, reactive oxygen species (ROS) interact with nitric oxide (NO) to provide an oxidant tone. This contributes to the mechanisms redistributing the fetal cardiac output, although the source of ROS is unknown. Here, we investigated whether ROS derived from xanthine oxidase (XO) contribute to the fetal peripheral vasoconstrictor response to hypoxia via interaction with NO-dependent mechanisms. Pregnant ewes and their fetuses were surgically prepared for long-term recording at 118 days of gestation (term approximately 145 days). After 5 days of recovery, mothers were infused i.v. for 30 min with either vehicle (n = 11), low dose (30 mg kg(-1), n = 5) or high dose (150 mg kg(-1), n = 9) allopurinol, or high dose allopurinol with fetal NO blockade (n = 6). Following allopurinol treatment, fetal hypoxia was induced by reducing maternal inspired O2 such that fetal basal P aO 2 decreased approximately by 50% for 30 min. Allopurinol inhibited the increase in fetal plasma uric acid and suppressed the fetal femoral vasoconstrictor, glycaemic and lactate acidaemic responses during hypoxia (all P < 0.05), effects that were restored to control levels with fetal NO blockade. The data provide evidence for the activation of fetal XO in vivo during hypoxia and for XO-derived ROS in contributing to the fetal peripheral vasoconstriction, part of the fetal defence to hypoxia. The data are of significance to the understanding of the physiological control of the fetal cardiovascular system during hypoxic stress. The findings are also of clinical relevance in the context of obstetric trials in which allopurinol is being administered to pregnant women when the fetus shows signs of hypoxic distress.

Maternal-to-fetal allopurinol transfer and xanthine oxidase suppression in the late gestation pregnant rat

Fetal brain hypoxic injury remains a concern in high-risk delivery. There is significant clinical interest in agents that may diminish neuronal damage during birth asphyxia, such as in allopurinol, an inhibitor of the prooxidant enzyme xanthine oxidase. Here, we established in a rodent model the capacity of allopurinol to be taken up by the mother, cross the placenta, rise to therapeutic levels, and suppress xanthine oxidase activity in the fetus. On day 20 of pregnancy, Wistar dams were given 30 or 100 mg kg(-1) allopurinol orally. Maternal and fetal plasma allopurinol and oxypurinol concentrations were measured, and xanthine oxidase activity in the placenta and maternal and fetal tissues determined. There were significant strong positive correlations between maternal and fetal plasma allopurinol (r = 0.97, P < 0.05) and oxypurinol (r = 0.88, P < 0.05) levels. Under baseline conditions, maternal heart (2.18 ± 0.62 mU mg(-1)), maternal liver (0.29 ± 0.08 mU mg(-1)), placenta (1.36 ± 0.42 mU mg(-1)), fetal heart (1.64 ± 0.59 mU mg(-1)), and fetal liver (0.14 ± 0.08 mU mg(-1)) samples all showed significant xanthine oxidase activity. This activity was suppressed in all tissues 2 h after allopurinol administration and remained suppressed 24 h later (P < 0.05), despite allopurinol and oxypurinol levels returning toward baseline. The data establish a mammalian model of xanthine oxidase inhibition in the mother, placenta, and fetus, allowing investigation of the role of xanthine oxidase-derived reactive oxygen species in the maternal, placental, and fetal physiology during healthy and complicated pregnancy.

Antenatal allopurinol reduces hippocampal brain damage after acute birth asphyxia in late gestation fetal sheep

Free radical-induced reperfusion injury is a recognized cause of brain damage in the newborn after birth asphyxia. The xanthine oxidase inhibitor allopurinol reduces free radical synthesis and crosses the placenta easily. Therefore, allopurinol is a promising therapeutic candidate. This study tested the hypothesis that maternal treatment with allopurinol during fetal asphyxia limits ischemia-reperfusion (I/R) damage to the fetal brain in ovine pregnancy. The I/R challenge was induced by 5 repeated measured compressions of the umbilical cord, each lasting 10 minutes, in chronically instrumented fetal sheep at 0.8 of gestation. Relative to control fetal brains, the I/R challenge induced significant neuronal damage in the fetal hippocampal cornu ammonis zones 3 and 4. Maternal treatment with allopurinol during the I/R challenge restored the fetal neuronal damage toward control scores. Maternal treatment with allopurinol offers potential neuroprotection to the fetal brain in the clinical management of perinatal asphyxia.

Long-term neuroprotective effects of allopurinol after moderate perinatal asphyxia: follow-up of two randomised controlled trials

OBJECTIVE

Free-radical-induced reperfusion injury has been recognised as an important cause of brain tissue damage after birth asphyxia. Allopurinol reduces the formation of free radicals, thereby potentially limiting the amount of hypoxia-reperfusion damage. In this study the long-term outcome of neonatal allopurinol treatment after birth asphyxia was examined.

DESIGN

Follow-up of 4 to 8 years of two earlier performed randomised controlled trials.

SETTING

Leiden University Medical Center, University Medical Center Groningen and University Medical Center Utrecht, The Netherlands.

PATIENTS

Fifty-four term infants were included when suffering from moderate-to-severe birth asphyxia in two previously performed trials.

INTERVENTION

Infants either received 40 mg/kg allopurinol (with an interval of 12 h) starting within 4 h after birth or served as controls.

MAIN OUTCOME MEASURES

Children, who survived, were assessed with the Wechsler Preschool and Primary Scales of Intelligence test or Wechsler Intelligence Scale for Children and underwent a neurological examination. The effect of allopurinol on severe adverse outcome (defined as mortality or severe disability at the age of 4-8 years) was examined in the total group of asphyxiated infants and in a predefined subgroup of moderately asphyxiated infants (based on the amplitude integrated electroencephalogram).

RESULTS

The mean age during follow-up (n=23) was 5 years and 5 months (SD 1 year and 2 months). There were no differences in long-term outcome between the allopurinol-treated infants and controls. However, subgroup analysis of the moderately asphyxiated group showed significantly less severe adverse outcome in the allopurinol-treated infants compared with controls (25% vs 65%; RR 0.40, 95%CI 0.17 to 0.94).

CONCLUSIONS

The reported data may suggest a (neuro)protective effect of neonatal allopurinol treatment in moderately asphyxiated infants.

Antenatal allopurinol for reduction of birth asphyxia induced brain damage (ALLO-Trial); a randomized double blind placebo controlled multicenter study

BACKGROUND

Hypoxic-ischaemic encephalopathy is associated with development of cerebral palsy and cognitive disability later in life and is therefore one of the fundamental problems in perinatal medicine. The xanthine-oxidase inhibitor allopurinol reduces the formation of free radicals, thereby limiting the amount of hypoxia-reperfusion damage. In case of suspected intra-uterine hypoxia, both animal and human studies suggest that maternal administration of allopurinol immediately prior to delivery reduces hypoxic-ischaemic encephalopathy.

METHODS/DESIGN

The proposed trial is a randomized double blind placebo controlled multicenter study in pregnant women at term in whom the foetus is suspected of intra-uterine hypoxia.Allopurinol 500 mg IV or placebo will be administered antenatally to the pregnant woman when foetal hypoxia is suspected. Foetal distress is being diagnosed by the clinician as an abnormal or non-reassuring foetal heart rate trace, preferably accompanied by either significant ST-wave abnormalities (as detected by the STAN-monitor) or an abnormal foetal blood scalp sampling (pH < 7.20).Primary outcome measures are the amount of S100B (a marker for brain tissue damage) and the severity of oxidative stress (measured by isoprostane, neuroprostane, non protein bound iron and hypoxanthine), both measured in umbilical cord blood. Secondary outcome measures are neonatal mortality, serious composite neonatal morbidity and long-term neurological outcome. Furthermore pharmacokinetics and pharmacodynamics will be investigated.We expect an inclusion of 220 patients (110 per group) to be feasible in an inclusion period of two years. Given a suspected mean value of S100B of 1.05 ug/L (SD 0.37 ug/L) in the placebo group this trial has a power of 90% (alpha 0.05) to detect a mean value of S100B of 0.89 ug/L (SD 0.37 ug/L) in the 'allopurinol-treated' group (z-test2-sided). Analysis will be by intention to treat and it allows for one interim analysis.

DISCUSSION

In this trial we aim to answer the question whether antenatal allopurinol administration reduces hypoxic-ischaemic encephalopathy in neonates exposed to foetal hypoxia.

TRIAL REGISTRATION NUMBER

Clinical Trials, protocol registration system: NCT00189007.

The value of umbilical artery Doppler velocimetry in the antenatal surveillance of uncomplicated monochorionic twin pregnancies

OBJECTIVES

To investigate the predictive value of abnormal umbilical artery Doppler findings on outcome in uncomplicated monochorionic (MC) twin pregnancies.

METHODS

Sixty-seven MC twin pregnancies, with antenatal care and delivery at the University Medical Center, Utrecht, The Netherlands, between 1999 and 2004, were studied. Pregnancies with antenatal signs of twin-to-twin transfusion syndrome were excluded. We analyzed the data according to both the last Doppler measurement of the umbilical artery before delivery and the presence of any abnormal Doppler measurement during the course of pregnancy. Risks of mortality and total neonatal morbidity were stratified according to the Doppler findings in one or both fetuses at the time of each standard ultrasound assessment in order to estimate the risk associated with an abnormal Doppler finding at or before that specific gestational age.

RESULTS

Mortality rates were similar in the normal and abnormal Doppler groups. Using both group definitions, total neonatal morbidity was higher in the abnormal Doppler group; this was significant at > 32 weeks' gestation, and was due to lower birth weight and earlier gestational age at delivery. There was no mortality at > or = 36 weeks in the abnormal Doppler group, but there were four perinatal deaths in the normal Doppler group. Gestational age at delivery was significantly lower when one or more abnormal Doppler findings had been present (median, 34 + 1 weeks vs. 36 + 3 weeks) and infants with abnormal Doppler findings weighed on average 261 g (95% CI, 21-502 g) less than those with normal findings.

CONCLUSIONS

In MC twins, abnormal Doppler flow of the umbilical artery identifies a subgroup at risk for preterm delivery, low birth weight and neonatal morbidity, but with a similar mortality risk to those with normal Doppler flow. At term, mortality occurred only in the group with normal Doppler findings, suggesting that fetal surveillance is insufficient in uncomplicated term MC twin pregnancies.