Effect of long-term cocaine administration to pregnant ewes on fetal hemodynamics, oxygenation, and growth

Does Prenatal Exposure to CNS Stimulants Increase the Risk of Cardiovascular Disease in Adult Offspring?

Prenatal exposure to an adverse uterine environment can have long lasting effects on adult offspring through DNA methylation, histone acetylation, and other epigenetic effects that alter gene expression and physiology. It is well-known that consumption of CNS stimulants such as caffeine, nicotine, amphetamines, and cocaine during pregnancy can adversely impact the offspring. However, most work in this area has focused on neurological and behavioral outcomes and has been limited to assessments in young offspring. The impact of prenatal exposure to these agents on the adult cardiovascular system has received relatively little attention. Evidence from both animal and human studies indicate that exposure to CNS stimulants during the gestational period can negatively impact the adult heart and vasculature, potentially leading to cardiovascular diseases later in life. This review discusses our current understanding of the impact of prenatal exposure to cocaine, methamphetamine, nicotine, and caffeine on the adult cardiovascular system.

Differential Patterns of Cocaine-Induced Organ Toxicity in Murine Heart versus Liver

To determine cocaine's toxicity in different organs, BALB/c mice were intraperitoneally injected daily for 15 days with either saline or cocaine: 10 mg/kg, 30 mg/kg, or 60 mg/kg. Cardiac function, hepatic pathophysiology, heart and liver apoptosis, and tumor necrosis factor (TNF-α) levels were analyzed. After administration of cocaine, cardiac function decreased. Inflammatory cell infiltration and eosinophilic contraction bands were visible in the hearts of mice treated with 60mg/kg cocaine. Moreover, histopathology demonstrated that cocaine caused hepatic necrosis. TdT-mediated dUTP nick end-labeling (TUNEL) staining and DNA ladder analysis indicated that cocaine caused apoptosis in both the heart and liver. Moreover, immunoassay showed that TNF-α levels significantly increased in the heart and liver with cocaine administration. However, our RT-PCR study showed that there was no significant difference in either the heart or liver in the levels of mRNA for TNF-α between cocaine-treated and saline control mice. The present study demonstrated that cocaine is toxic to multiple organs, and at low dose can induce hepatic damage without gross pathological injury to the heart. The results suggest that the liver is more sensitive than the heart to cocaine toxicity, and induction of apoptosis or TNF-α elevation may be a common mechanism responsible for cocaines toxicity.

Prenatal methamphetamine differentially alters myocardial sensitivity to ischemic injury in male and female adult hearts

Methamphetamine is one of the most common illicit drugs abused during pregnancy. The neurological effects of prenatal methamphetamine are well known. However, few studies have investigated the potential effects of prenatal methamphetamine on adult cardiovascular function. Previous work demonstrated that prenatal cocaine exposure increases sensitivity of the adult heart to ischemic injury. Methamphetamine and cocaine have different mechanisms of action, but both drugs exert their effects by increasing dopaminergic and adrenergic receptor stimulation. Thus the goal of this study was to determine whether prenatal methamphetamine also worsens ischemic injury in the adult heart. Pregnant rats were injected with methamphetamine (5 mg·kg(-1)·day(-1)) or saline throughout pregnancy. When pups reached 8 wk of age, their hearts were subjected to ischemia and reperfusion by means of a Langendorff isolated heart system. Prenatal methamphetamine had no significant effect on infarct size, preischemic contractile function, or postischemic recovery of contractile function in male hearts. However, methamphetamine-treated female hearts exhibited significantly larger infarcts and significantly elevated end-diastolic pressure during recovery from ischemia. Methamphetamine significantly reduced protein kinase Cε expression and Akt phosphorylation in female hearts but had no effect on these cardioprotective proteins in male hearts. These data indicate that prenatal methamphetamine differentially affects male and female sensitivity to myocardial ischemic injury and alters cardioprotective signaling proteins in the adult heart.

The maternal, fetal, and neonatal effects of cocaine exposure in pregnancy

Despite multiple efforts to reduce the use of illicit drugs, the epidemic of addiction continues to be a significant public health issue. Through its easy availability, the number of people afflicted with this addiction continues to rise, including women of childbearing age. Secondarily, any health care crisis that occurs in this age group of women will have potential implications in pregnancy, infancy, and childhood. The use of cocaine alone or in conjunction with other illicit drugs, combined with the normal physiological cardiovascular changes in pregnancy, leads to a myriad of pathophysiological changes, thereby placing the life of the pregnant cocaine user, as well as the health status of their unborn fetus and neonate at risk for adverse outcomes. As more data are available, the long-term physical, mental, and developmental sequelae for children exposed to cocaine in utero prove that this public health crisis has serious implications. The pregnancy-specific maternal, fetal, and neonatal risks of cocaine use during the antepartum period are reviewed.

Optical coherence tomography captures rapid hemodynamic responses to acute hypoxia in the cardiovascular system of early embryos

BACKGROUND

The trajectory to heart defects may start in tubular and looping heart stages when detailed analysis of form and function is difficult by currently available methods. We used a novel method, Doppler optical coherence tomography (OCT), to follow changes in cardiovascular function in quail embryos during acute hypoxic stress. Chronic fetal hypoxia is a known risk factor for congenital heart diseases (CHDs). Decreased fetal heart rates during maternal obstructive sleep apnea suggest that studying fetal heart responses under acute hypoxia is warranted.

RESULTS

We captured responses to hypoxia at the critical looping heart stages. Doppler OCT revealed detailed vitelline arterial pulsed Doppler waveforms. Embryos tolerated 1 hr of hypoxia (5%, 10%, or 15% O(2) ), but exhibited changes including decreased systolic and increased diastolic duration in 5 min. After 5 min, slower heart rates, arrhythmic events and an increase in retrograde blood flow were observed. These changes suggested slower filling of the heart, which was confirmed by four-dimensional Doppler imaging of the heart itself.

CONCLUSIONS

Doppler OCT is well suited for rapid noninvasive screening for functional changes in avian embryos under near physiological conditions. Analysis of the accessible vitelline artery sensitively reflected changes in heart function and can be used for rapid screening. Acute hypoxia caused rapid hemodynamic changes in looping hearts and may be a concern for increased CHD risk.

Fetal cerebrovascular response to chronic hypoxia—implications for the prevention of brain damage

Fetal hypoxia is one of the leading causes of perinatal morbidity and mortality. One of the most severe sequels of fetal hypoxic insult is the development of perinatal brain lesions resulting in a spectrum of neurological disabilities, from minor cerebral disorders to cerebral palsy. One of the most important fetal adaptive responses to hypoxia is redistribution of blood flow towards the fetal brain, known as the 'brain sparing effect'. The fetal blood flow redistribution in favor of the fetal brain can be detected and quantified by the Doppler cerebral/umbilical ratio (C/U ratio = cerebral resistance index (CRI)/umbilical resistance index (URI)). Our studies on animal models and human fetuses have demonstrated clearly that this phenomenon cannot prevent the development of perinatal brain lesions in the case of severe or prolonged hypoxia. Fetal deterioration in chronic and severe hypoxia is characterized by the disappearance of the physiological cerebral vascular variability (vasoconstriction and vasodilatation), followed by an increase in cerebral vascular resistance. However, our latest study on growth-restricted and hypoxic human fetuses has shown that perinatal brain lesions can develop even before the loss of cerebrovascular variability. The fetal exposure to hypoxia can be quantified by using a new vascular score, the hypoxia index. This parameter, which takes into account the degree as well as duration of fetal hypoxia, can be calculated by summing the daily % C/U ratio reduction from the cut-off value 1 over the period of observation. According to our results, the use of this parameter, which calculates the cumulative, relative oxygen deficit, could allow for the first time the sensitive and reliable prediction and even prevention of adverse neurological outcome in pregnancies complicated by fetal hypoxia.

Early fetal hypoxia leads to growth restriction and myocardial thinning

Hypoxia is necessary for fetal development; however, excess hypoxia is detrimental. Hypoxia has been extensively studied in the near-term fetus, but less is known about earlier fetal effects. The purpose of this study was to determine the window of vulnerability to severe hypoxia, what organ system(s) is most sensitive, and why hypoxic fetuses die. We induced hypoxia by reducing maternal-inspired O2 from 21% to 8%, which decreased fetal tissue oxygenation assessed by pimonidazole binding. The mouse fetus was most vulnerable in midgestation: 24 h of hypoxia killed 89% of embryonic day 13.5 (E13.5) fetuses, but only 5% of E11.5 and 51% of E17.5 fetuses. Sublethal hypoxia at E12.5 caused growth restriction, reducing fetal weight by 26% and protein by 45%. Hypoxia induced HIF-1 target genes, including vascular endothelial growth factor (Vegf), erythropoietin, glucose transporter-1 and insulin-like growth factor binding protein-1 (Igfbp-1), which has been implicated in human intrauterine growth restriction (IUGR). Hypoxia severely compromised the cardiovascular system. Signs of heart failure, including loss of yolk sac circulation, hemorrhage, and edema, were caused by 18-24 h of hypoxia. Hypoxia induced ventricular dilation and myocardial hypoplasia, decreasing ventricular tissue by 50% and proliferation by 21% in vivo and by 40% in isolated cultured hearts. Epicardial detachment was the first sign of hypoxic damage in the heart, although expression of epicardially derived mitogens, such as FGF2, FGF9, and Wnt9b was not reduced. We propose that hypoxia compromises the fetus through myocardial hypoplasia and reduced heart rate.

New Doppler index for prediction of perinatal brain damage in growth-restricted and hypoxic fetuses

OBJECTIVE

To evaluate the new vascular score, hypoxia index (HI), in the prediction of sonographically detected structural brain lesions in neonates within the first week after delivery of growth-restricted fetuses.

METHODS

This prospective study included 29 growth-restricted fetuses delivered between 31 and 40 gestational weeks. Doppler umbilical artery (UA) and middle cerebral artery (MCA) resistance indices (RI) were recorded at 48-h intervals for at least 2 weeks before delivery. The cerebroumbilical ratio (C/U ratio = MCA-RI/UA-RI) and the HI (the sum of the daily reductions in C/U ratio, i.e. percentage below the cut-off value of 1, over the period of observation) were calculated. After delivery, neonatal outcome was evaluated according to obstetric parameters and ultrasound examinations of the brain. Doppler indices, C/U ratio and HI, as well as neonatal clinical and biochemical parameters, were tested as potential predictors of brain lesions using the C4.5 data-mining algorithm.

RESULTS

Neonatal brain lesions were detected in 13 growth-restricted fetuses. Of all the parameters tested by the C4.5 data-mining algorithm, only HI was identified as a predictor of neonatal brain lesions. HI also showed better correlation with neonatal biochemical parameters, such as umbilical venous partial pressure of oxygen and umbilical venous pH, compared with the C/U ratio.

CONCLUSIONS

HI, which takes into account cumulative oxygen deficit, could significantly improve the prediction of a poor neurological outcome in pregnancies complicated by growth restriction and hypoxia.

New data about embryonic and fetal neurodevelopment and behavior obtained by 3D and 4D sonography

The development of the human central nervous system (CNS) begins in the early embryonic period and proceeds through a sequence of very complicated processes long after delivery. Although the neurodevelopmental processes are genetically determined, their complexity and intensity implicates the vulnerability of the CNS to number of environmental factors. There is substantial evidence to show that many neurological problems, from minor cerebral dysfunction to the cerebral palsy, originate form the prenatal, rather than perinatal or postnatal periods of life. A variety of neurological and neuropsychiatric diseases is nowadays considered to originate, at least partly, from the prenatal incidents. In most of these conditions, there is no reliable parameter for detection or prediction of cerebral lesions and there is an urgent need to develop strategies that would enable the early detection of cerebral lesions or indications that such lesions might occur. The new, advanced, imaging techniques such as 3-dimensional and 4-dimensional sonography, opened a new perspective for the investigation of structural and functional development of fetal CNS. The application of these techniques might improve our understanding of the prenatal neurodevelopmental events and possibly facilitate the development of diagnostic strategies for early detection or prevention of brain dysfunctions and damage.

Fetal Doppler Hypoxic index for the prediction of abnormal fetal heart rate at delivery in chronic fetal distress

OBJECTIVE

To design a Doppler Hypoxic index (HI), which takes into account both the duration and the intensity of fetal flow redistribution (i.e. hypoxia) for predicting the occurrence of abnormal fetal heart rate (FHR) at delivery.

METHOD

Sixty-six pregnancies with hypertension and/or growth retardation (IUGR) were investigated (age: 23+/-5 years; primigravidas: 30%, CS 59%; hospitalisation: 10+/-8 days, IUGR (<10 c) 82%, intensive care 23%, fetal death 1). Umbilical (URI) and cerebral (CRI) Doppler resistance indices, and the C/U ratio (CRI/URI) were measured every 2 days from admission to delivery. HI was calculated by summing the daily %C/U reduction (in % from normal cut-off limit 1.1) over the period of observation (or mean C/U reduction in % from 1.1 x number of days of observation). Doppler C/U and HI were compared with fetal heart rate (FHR) traces, and perinatal data.

RESULTS

HI > 160% was associated with abnormal FHR in 80% of the cases (PPV = 87%, NPV = 88%). HI > 160% predicted the occurrence of abnormal FHR 8+/-6 days before they happened.

CONCLUSION

A combination of intensity and duration of the fetal flow redistribution (i.e. hypoxia) evaluated by Doppler is correlated with the occurrence of abnormal fetal heart rate.

Chronic prenatal exposure to cocaine alters cerebrovascular responses in newborn pigs

Maternal cocaine abuse may increase the incidence of perinatal asphyxia. In nonexposed asphyxiated neonates, decreased cerebrospinal fluid (CSF) cAMP concentrations are associated with poor neurological outcome. On the other hand, cocaine increases central nervous system (CNS) cAMP. Therefore, we hypothesized that in utero cocaine exposure may increase brain cAMP and thereby preserve cerebrovascular responses to cAMP-dependent stimuli following asphyxia. Pregnant pigs received either cocaine (1 mg/kg, i.v.) twice weekly during the last trimester or normal saline vehicle (sham-control) and were allowed to deliver vaginally at term. Cranial windows were implanted in the newborn pigs within the first week of life and used to collect CSF for cAMP determinations and to assess changes in pial arteriolar diameters (PAD). In the first part of the study, pial arteriolar responses to different vasodilator and vasoconstrictor stimuli were evaluated in piglets prior to asphyxia (n = 20). In newborn pigs exposed to cocaine, cerebrovascular responses to hypercapnia and norepinephrine were significantly exaggerated compared to controls. Then, piglets were randomly selected for the second part of the study that involved prolonged asphyxia (n = 12). In cocaine-exposed but not sham-control piglets, CSF cAMP increased markedly during asphyxia. In the sham piglets, but not the cocaine-exposed piglets, CSF cAMP fell progressively below the baseline during recovery. Cerebrovascular reactivity to cAMP-dependent stimuli (hypercapnia and isoproterenol) was preserved during recovery from asphyxia in the cocaine-exposed piglets but significantly attenuated in the sham controls. We conclude that piglets with chronic prenatal exposure to cocaine show exaggerated cerebrovascular responses to vasogenic stimuli and preserved cAMP-dependent cerebral vasoreactivity following asphyxia.

Fetal biophysical profile and cerebro-umbilical ratio in assessment of brain damage in growth restricted fetuses

OBJECTIVE

To examine the relationship between fetal biophysical profile (FBP), Doppler cerebro-umbilical (C/U) ratio and neonatal neurosonography in growth restricted newborns.

STUDY DESIGN

This prospective study included 87 growth restricted fetuses from 28 to 42 weeks of gestation. The FBP and C/U ratio were assessed twice a week. Within 48h and on the seventh day after birth, neonatal neurosonography was performed as the outcome parameter.

RESULTS

Brain damage was detected, by neurosonography, in 34 newborns with intrauterine growth restriction (IUGR). Severe periventricular echodensities (PVE) were ultrasonographically verified in eleven infants. Intraventricular or intraparenchymal hemorrhage (severe intracranial hemorrhage ICH) was detected in seven infants, and subependymal hemorrhage (SEH) in nine infants with IUGR. Porencephalic cysts, as a result of chronic intrauterine hypoxia, were found in four infants, and brain atrophy was detected in one case. Nonspecific ultrasonographic changes were observed in two newborns. The FBP and C/U ratio were statistically significantly associated with neurosonographicaly verified neonatal brain lesions (P < 0.001).

CONCLUSIONS

The FBP and the C/U ratio represent the useful indicators for early detection and assessment of fetal hypoxia. They may also be parameters for the prediction of neonatal neurosonography findings in newborns with IUGR.

Acute reversible placental dysfunction and abnormal fetal heart rate at delivery

Acute placental dysfunction induced by malaria is characterized by umbilical artery resistance increase and cerebral artery resistance decrease during the crisis. The objective was to evaluate the sensitivity and specificity of fetal Doppler indices and crisis duration for predicting abnormal fetal heart rate (aFHR) at delivery several weeks after the crisis.

METHOD

Every day during the crisis, the umbilical and cerebral resistance indices were measured by Doppler. These indices allowed evaluation of the amplitude of the fetal flow redistribution (C/U = cerebral resistance/umbilical resistance ratio), the duration of the flow redistribution period (i.e. crisis duration) and the Hypoxic index (HI) (mean %C/U change x crisis duration).

RESULTS

POPULATION

46 pregnancies. Mean duration of the flow redistribution period 8+/-3.2 days, mean C/U change -9%+/-6; Hypoxic index -86+/-75; prematures 48%; aFHR 30%). Hypoxic index >150 predicted occurrence of aFHR with high sensitivity and specificity (83%/88%). The presence of abnormal flow distribution (C/U<1.1) and the duration of the period with flow disturbance (>8 days) predicted aFHR at delivery with a sensitivity of 45 and 48% and a specificity of 82 and 84%.

CONCLUSION

The Hypoxic index was more predictive of aFHR at delivery than the amplitude or the duration of the fetal flow redistribution triggered by placental insufficiency.

Doppler assessment of the fetal cerebral hemodynamic response to moderate or severe maternal anemia

OBJECTIVE

The purpose of this study was to evaluate the fetal vascular adaptation to moderate and severe maternal anemia.

STUDY DESIGN

Biometry; amniotic fluid index; uterine, cerebral, and umbilical Doppler; and maternal hemoglobin level were measured at admission and 8 days after treatment.

RESULTS

Group 1 consisted of 16 pregnancies (maternal hemoglobin level, 6.9 +/- 0.6 g/100 mL); group 2 consisted of 23 pregnancies (maternal hemoglobin level, 5 +/- 0.6 g/100 mL). At admission the cerebral and cerebral/umbilical Doppler indexes, amniotic index, and biometry were lower in group 2. The uterine index was normal in both groups. An abnormal fetal heart rate was found in group 2 only (48%). At day 8, maternal hemoglobin level and amniotic index increased more in group 2 than in group 1. The cerebral index and the cerebral-to-umbilical resistance ratio increased only in group 2. The abnormal fetal heart rate disappeared in group 2.

CONCLUSION

Only severe maternal anemia (maternal hemoglobin level, <6 mg/L) triggered fetal cerebral vasodilation and reduced amniotic volume.

Fetal flow redistribution to the brain in response to malaria infection: does protection of the fetus against malaria develop over time?

OBJECTIVE

Malaria during pregnancy induces deterioration of placental function, resulting in transient fetal hypoxia. Our objective was to evaluate the sensitivity and specificity of fetal Doppler indices for prediction of abnormal fetal heart rate at delivery and to compare the amplitude of the fetal vascular response to malaria in 2 groups of fetuses (1994 and 1996) separated by an interval of 2 years.

METHODS

Every day during the crisis, the umbilical and cerebral resistance indices, the cerebral-umbilical resistance ratio, and the hypoxic index (mean percent cerebral-umbilical resistance ratio change x crisis duration) were calculated.

RESULTS

In group 2 (1996), the duration of the flow redistribution period was about 7 days (mean cerebral-umbilical resistance ratio change +/- SD, 7%+/-4%; hypoxic index, 49+/-26; premature, 35%; and abnormal fetal heart rate, 17.5%). A hypoxic index greater than 150 predicted abnormal fetal heart rate with high sensitivity and specificity (group 1, 80% and 85%; and group 2, 100% and 91 %). Moreover, in group 2 (1996), the amplitude of the fetal vascular response and the rate of long-duration crisis were significantly lower than in group 1 (1994; P < .01). Nevertheless, the hypoxic index was much more predictive of fetal heart rate at delivery than the amplitude or duration (i.e., crisis duration) of the flow redistribution.

CONCLUSIONS

The hypoxic index value during the crisis allowed prediction of abnormal fetal heart rate at delivery. In group 2, the absence of a long-term flow redistribution period and the smaller hemodynamic changes (lower hypoxic index) associated with a lower occurrence of abnormal fetal heart rate could be related to improvement of pregnancy management, acquired protection during the interval between the 2 studies, or both.

Fetal vascular response to maternal deep-vein thrombosis and subsequent heparin therapy

The fetal umbilical and cerebral Doppler changes were recorded in a 27-year-old primigravida referred at 38 weeks for the treatment of an iliofemoral vein thrombosis. On admission and in comparison to a previous Doppler assessment systematically performed during growth scan at 37 weeks, the umbilical resistance index (URI) demonstrated an increase of 19%, the cerebral resistance index (CRI) a reduction of 15% and the cerebral-umbilical (C/U) ratio a decrease of 29% reaching the lowest value of 1.05. Under intravenous heparin therapy, Doppler normalisation was observed within 1 week and the mother delivered a healthy, non-hypoxemic baby by caesarean section at 39 weeks and 2 days. This observation suggests that deep-vein thrombosis (DVT) may, in some cases, be responsible for transient fetal hypoxia. Moreover, treatment with intravenous heparin had a direct beneficial effect on the fetus as it improved placental hemodynamics and fetal oxygenation.

Neurosteroid modulation of embryonic neuronal survival in vitro following anoxia

Neurosteroids are synthesized de novo in the brain from cholesterol or peripheral steroid precursors and modulate inhibitory gamma-aminobutyric acid (GABA(A)) and excitatory N-methyl-D-aspartate (NMDA) receptors. Evidence indicates that neurosteroids are neuroprotective and important during neurodevelopment. We tested the hypothesis that neurosteroids increase embryonic neuronal survival following anoxia in rat embryonic day 18 cerebral cortical cultures to examine potential neurosteroid modulation of this insult during early development. Twenty-four hours after plating in serum-free medium, cultures were exposed to DHEA, DHEAS, or allopregnanolone (10(-10), 10(-8), or 10(-6) M), or vehicle, for 24 h (n=9 per treatment condition). Cultures were then subjected to anoxia for 2 h and subsequently reincubated for 24 h prior to neuron immunostaining with microtubule-associated protein 2 (MAP-2) antibody. Supernatant from DHEA and DHEAS-exposed cultures was tested for 17beta-estradiol metabolite formation by radioimmunoassay. DHEA 10(-6) and 10(-8) M significantly increased neuron survival by 85-87% following anoxia. DHEAS 10(-6) M significantly increased neuron survival by 74% following anoxia, but DHEAS 10(-10) M decreased neuron survival after this insult. Allopregnanolone had modest effects on neuron survival that did not attain statistical significance. 17beta-Estradiol concentrations were below the limit of detection in all specimens tested (sensitivity 4.7 nM). Our data indicate that pretreatment with DHEA and DHEAS at physiologically relevant concentrations promotes neuronal survival following anoxia in embryonic rat cerebral cortical cultures, and that these effects are not secondary to 17beta-estradiol metabolite formation. DHEA and DHEAS modulation of anoxia in embryonic neurons may be relevant to disorders of neurodevelopment involving this insult.

Hypoxic induction of prolyl 4-hydroxylase alpha (I) in cultured cells

Accumulated evidence indicates that hypoxia activates collagen synthesis in tissues. To explore the molecular mechanism of activation, we screened genes that are up-regulated or down-regulated by hypoxia. Fibroblasts isolated from fetal rat lung were cultured under hypoxia. Differential display technique showed that the mRNA level of prolyl 4-hydroxylase (PH) alpha(I), an active subunit that catalyzes the oxygen-dependent hydroxylation of proline residue in procollagen, increased 2-3-fold after an 8-h exposure to hypoxia. This elevated level was maintained over 40 h and returned to the basal level after reoxygenation. The transcription rate, protein level, and hydroxyproline content (an indicator of the prolyl hydroxylation) were all elevated by hypoxic culture. Analysis of the promotor region of PHalpha(I) gene indicated that a motif similar to hypoxia-responsive element (HRE) of hypoxia-inducible genes such as erythropoietin, was identified within a 120-base pair sequence upstream of the transcription start site. Luciferase reporter assay and mutational analysis showed that a site similar to the HRE in this motif is functionally essential to hypoxic response. Electrophoretic mobility shift assay revealed that hypoxia-inducible factor-1 was stimulated and bound to the PHalpha(I) HRE upon hypoxic challenge. Our results indicate that PHalpha(I), an essential enzyme for collagen synthesis, is a target gene for hypoxia-inducible factor-1.

Brain damage and hypoxia in an ovine fetal chronic cocaine model

OBJECTIVE

To assess the development of brain damage in an ovine fetal chronic cocaine model. To evaluate the effect of isolated hypoxic tests on this model and to correlate hemodynamic findings (brain-sparing effect) following fetal hypoxia and the occurrence of brain damage.

STUDY DESIGN

Fifteen ewes were divided into a control group (n=7) and a cocaine treated group (n=8). From day 65 to day 134 the cocaine treated animals received a daily (5 days per week) intramuscular injection (2 mg/kg cocaine) and the control animals a placebo injection (2 ml of isotonic solution). Both groups underwent hypoxic tests (cord compression (3 min) and aortic compression (1 min)) at 90 and 134 days. In addition, anesthesia for magnetic resonance imaging (MRI) examination was carried out at 125 days. Fetal blood samples were collected during both series of hypoxic tests and the cerebral and umbilical flows were monitored by Doppler. Samples from 25 brains (control n = 10; cocaine n= 15) were processed for light and electron microscopic examination. Quantification of brain damage was done on semithin sections from six areas of cortex and germinal matrix on each fetus.

RESULTS

Similar forms of brain damage (selective neuronal loss limited to the parasaggital cortex, striatum, hippocampus and Purkinje cells) was present in both groups but lesions were more frequent in the cocaine treated group as shown by quantitative analysis for the proportion of abnormal capillaries (65% vs. 35%), capillary edema (61% vs. 34%) and abnormal neurons showing delayed neuronal degeneration (DND) (66% vs. 36%) in the cocaine and control group respectively. There was no significant difference in immunoreactivity for glial fibrillary acidic protein (GFAP) but it was more marked in the cerebellum of cocaine treated animals. Fetal blood samples showed a moderate sustained hypoxia and Doppler findings demonstrated the presence of a brain sparing effect associated with increased uterine and umbilical vascular resistance in the cocaine treated group. Nevertheless, the amplitude of the heart rate increase and cerebral dilatation was significantly lower in the cocaine treated animals.

CONCLUSION

This ovine fetal chronic cocaine model showed the presence of brain damage. Cocaine treatment seems to potentiate the effect of the hypoxic tests. Independent of the cause, the brain damage developed in the presence of brain sparing effect, strongly suggesting that this phenomenon is a sign of a pathological fetal condition and no guarantee that it will prevent tissue damage.

Cerebral MRI on fetuses submitted to repeated cocaine administration during the gestation: an ovine model

The aim of this study was to determine the role of Magnetic Resonance Imaging (MRI) in investigating fetal cerebral lesions induced by long term exposure to cocaine during sheep pregnancy. Cerebral Magnetic Resonance Imaging was performed on two groups of fetuses at 125 days of gestation (normal gestation: 145 days). The control group consisted of eight fetuses of four pregnant ewes. The study group consisted of eight fetuses of four pregnant ewes receiving daily 140 mg/kg injection of cocaine from day 60 until delivery. The following MR sequences were applied: T1-weighted FLASH, and T2-weighted Fast-Spin-Echo. Cerebral images were evaluated semi quantitatively using the following criteria: Heterogenicity, contrast between grey and white matter, contours irregularity, hyposignal, lateral ventricle sizes. The brightness distribution and homogenicity of the images were analysed by means of edge pair distributions using a new computerized method originally designed for ultrasound images analysis developed by Ultrasight inc (USA). (1) Flash T1: Heterogenic areas and irregular contours were more frequent in cocaine exposed fetuses. The contrast between grey and white matter was more important in the cocaine group. Hyposignal was found only in the cocaine group. Enlarged lateral ventricle occurred more frequently in the cocaine group. (2) Spin echo T2: The contrast between grey and white matter was higher and the contours of the brain more irregular in the cocaine group. Heterogenicity and hyposignal were also more frequent in this group but the difference with the control group was not significant. The computerized analysis of the contrast density on the cerebral images showed that 88% of the areas exceeding the reference level concerned the cocaine group, while only 14% of the areas exceeding the reference level concerned the control group. Long term exposure to cocaine induces cerebral tissue modifications, in favor of an advanced maturation and the development of hypoxic lesions. The histology of the brains confirmed in the cocaine group, the existence of hypoxic lesions with gliosis, perivascular edema and hemorrhages, and neuronal death.