Cocaine binding sites in fetal rat brain: implications for prenatal cocaine action

Binding of [³H]cocaine to membrane preparations from whole fetal rat brain was studied. High-affinity binding (10 nM cocaine) was detected as early as gestational day (GD) 15 and steadily increased across subsequent development. Saturation studies comparing [³H]cocaine binding at GD20 and adulthood yielded similar K_D values, and LIGAND analyses favored a two-site model if an extended range of [³H]cocaine concentrations was used. Various monoamine uptake inhibitors displaced labeled cocaine with potencies consistent with the idea that [³H]cocaine labels the dopamine (DA), serotonin (5-HT), and possibly also the norepinephrine (NE) transporters in whole fetal brain preparations. Synaptosomal DA uptake was well developed by GD20, as was the potency of cocaine to inhibit such uptake. The results indicate that functional, monoamine transporter related cocaine binding sites are present in the fetal rat brain. Such sites are likely to play an important role in mediating the direct interactions of prenatally-administered cocaine with developing monoaminergic systems in both animals and humans.Some of these data were published in preliminary form in: Meyer JS (1992) Prenatal neurochemistry of cocaine. Ann NY Acad Sci 654:487–488     

Altered maternal thyroid function: fetal and neonatal development of rat

Influence of maternal thyroid status on fetal and neonatal development of rats has been studied. Maternal hypothyroidism resulted impaired reproduction and intrauterine growth retardation of offsprings as revealed by their reduced body weight, heart weight, body length and tail length. Offsprings born to hypothyroid mothers showed very high rate of mortality and none of them survived beyond eight days. Maternal hyperthyroidism did not cause any abnormality on reproduction. Hyperthyroid mothers showed increased rate in body weight gain during pregnancy which was associated with increased weight of body and heart of fetuses born to hyperthyroid mothers. Plasma thyroxine was not measurable in fetus from hypothyroid mothers till 21st day of gestation. The results of the present study showed that maternal thyroid status plays an important role in fetal and neonatal growth and development.     

Cocaine concentrations in fetal C57BL/6 mouse brain relative to maternal brain and plasma

Cocaine concentrations in maternal plasma and brain and fetal brain of mice were evaluated as a model for fetal brain exposure during maternal cocaine use. On days 12–18 of gestation, mice (C57BL/6; N = 5–7/group) received SC cocaine-HCl: 20 or 40 mg/kg. Maternal plasma and brain (accumbens and caudate nuclei removed), and fetal brain were collected at 0.5, 1, and 2 h following the last injection. Analysis was by GC-MS. Brain cocaine levels in the dams declined from 9.6 to 3.4 and 20.9 to 12.5 mg/g during the 0.5–1-h period after the low and high doses, respectively, and were 7.5–14.3 times greater than plasma levels. The corresponding fetal brain concentrations changed from 1.6 to 1.3 and 2.9 to 3.4 mg/g. By 2 h, brain cocaine concentrations in dams declined to approximately 10% of their 0.5-h values, with a slower drug decay occurring in fetal brain. Maternal plasma cocaine concentrations correlated with those of maternal brain (r = 0.94, p < 0.01) and fetal brain (r = 0.69, p < 0.01). The present results indicate that cocaine accumulates to a lesser extent in fetal brain than in maternal brain of C57BL/6 mice; however, the duration of exposure appears to be more sustained in the fetus, a phenomenon that may have toxicological implications for human in utero cocaine exposure.     

Cocaine detection during toxicology screening of a university medical center patient population

The frequency of detection of cocaine and/or its major metabolite, benzoylecgonine, during toxicology screening of a university medical center patient population was evaluated by retrospective review of the results of the 2,200 toxicology screens performed during 1986 on either urine or urine in conjunction with blood. Of these screens, 234 (10%) were positive for cocaine and/or its metabolite--a substantial increase from the 1% noted for the year 1978 at this medical center. Men and women were represented equally with the most common age range being 21 to 30 years for both. Most adults (64%) were located on either the obstetrics or the trauma services. In 37 instances cocaine was detected in neonates, presumably due to transplacental transmission. Cocaine and/or its metabolite were found either alone or in combination with other drugs with about equal frequency. The most common other drugs were ethanol, morphine, amphetamine, methamphetaine, and phencyclidine. Cocaine detection increased throughout the study period with 68% of positives occurring from July through December 1986. Analysis of cocaine and/or benzoylecgonine should be an integral part of toxicology screening performed on a university medical center patient population.     

Drugs of abuse in maternal hair and paired neonatal meconium: an objective assessment of foetal exposure to gestational consumption

In a prospective sample of 80 mother‐infant dyads, we investigated whether drugs of abuse in maternal hair measured during the pregnancy trimesters were also present in neonatal meconium. Principal drugs of abuse were analyzed in the three consecutive maternal hair segments and meconium samples by ultra‐performance liquid chromatography tandem mass spectrometry assay. Of the 80 mothers, 32 (40%) presented one or more hair shafts with at least one of the analyzed drugs of abuse and/or its metabolites. The drug of abuse with a higher prevalence in our study population was methamphetamine: 19 mothers had methamphetamine in one or more hair segments (59.4%). The second most detected drug of abuse was cocaine; nine mothers presented cocaine in one or more hair segments (28.1%). Nineteen pregnant women consumed at least one drug of abuse during the first trimester, ten continued consuming drugs of abuse during the second trimester; and nine consumed until the end of pregnancy. Five of the nine newborns from mothers who consumed drugs during the whole pregnancy showed drugs of abuse in meconium samples. Newborns from the 23 remaining mothers with one or two hair shafts positive to drugs of abuse did not present drugs in their meconium. Indeed from these results, it seems that discontinuous and/or sporadic consumption during pregnancy could produce a negligible transplacental passage and hence negative results in meconium. Furthermore, the role of placenta in the metabolism and excretion of drugs of abuse is still to be precisely investigated. Copyright © 2015 John Wiley & Sons, Ltd.     

Cocaine in pregnancy: analysis of fetal risk.

During the last decades there has been a substantial increase in the recreational use of cocaine in young adults and parallelly there has been an increase of its use by pregnant women. We analyzed all published papers on cocaine use in pregnancy and found that for most endpoints studied (eg, prematurity, head circumference) there were many studies showing effects and many showing no effects. Upon meta-analysis, most of these effects could not be shown significant when compared to control groups. In a prospective study in Toronto, babies exposed to cocaine during the first trimester only had Bayley scores at 18-mo of life that were identical to unexposed babies or to those exposed to canabinoids. Motherisk presently counsels women who discontinue cocaine use in the first trimester of pregnancy that there is no increased developmental risk for the baby.     

Cocaine: its effects on maternal and child health.

Cocaine abuse has become one of America's leading public health problems. Its use throughout pregnancy is associated with an increased risk of abruptio placentae, stillbirth, and preterm labor. Cocaine-associated neonatal complications include congenital malformations, decreased fetal growth, seizures, cerebral infarction and hemorrhage, auditory system deficits, sudden infant death syndrome, cardiac arrhythmias, necrotizing enterocolitis, and behavioral changes. Children followed throughout the first year of life continue to show developmental delay. Infants and children growing up in cocaine-abusing families are at risk for drug-related injuries. Accidental and intentional intoxication has occurred in infants and children from the smoke of freebase cocaine. The drug has also caused intoxication in breast-feeding infants. Adolescents experimenting with cocaine are at risk, with an apparently high frequency of seizures and loss of consciousness, as well as behavioral changes and psychosocial dysfunction.     

Cocaine exposure in utero: perinatal development and neonatal manifestations--review.

The question of whether cocaine exposure in utero increases the risk of major structural malformations remains controversial. Most animal studies have demonstrated that cocaine can have a teratogenic effect. The ultimate association between cocaine exposure and fetal development must be inferred from human data. The relative effects of cocaine exposure, exposure to other illicit drugs and alcohol and deficient prenatal care are difficult to assess. Little specific information is available about the amount, duration, and timing of cocaine use during the nine months of pregnancy. Unlike the case with many other teratogens, cocaine exposure at any point in pregnancy can result in some abnormality. The extent of damage and the organ involved depend on the particular stage of morphogenesis. A large scale prospective human study is needed to confirm the suggested teratogenic effects. Since it involves an illicit drug such a study is obviously difficult to perform.     

Genetic factors in toxicology: implications for toxicological screening

Methods of assessing the toxicity of xenobiotics have improved substantially during the last decade. However, as compounds become generally safer, the problem of individual variation in response assumes increasing relative importance. Environmental factors such as age, health and nutritional status, and interactions with other xenobiotics account for some of this variation, but genetic differences between individuals and races have important implications. In a few cases, Mendelian loci which control drug susceptibility (e.g., to isoniazid) have been described. However, in most cases the exact mode of inheritance has not yet been determined due to the problems of carrying out genetic studies in man. It is well established that many loci that are polymorphic in man are also so in laboratory animals, so much of this genetic variation should be picked up in preclinical screening, and could be used to more accurately predict potential variation in toxicity in man. Unfortunately, most toxicologists use only a single stock of laboratory animals, which does not show whether the response to a given xenobiotic is under genetic control. The design of animal tests would be improved by using more than one strain of genetically defined animals, and by paying more attention to genetic variation in responses to xenobiotics, both in animals and man.     

Cocaine disrupts pup-induced maternal behavior in juvenile and adult rats

Impaired onset of maternal behavior in first generation rat dams was previously correlated with rearing by cocaine-treated dams and prenatal cocaine exposure. Pup-induced maternal behavior in non-lactating rats has not been examined with regard to cocaine exposure and rearing conditions. First generation male and female juveniles and young adult males reared by cocaine-treated or control dams and prenatally exposed to either cocaine or control conditions were tested for pup-induced maternal behavior at postnatal days 28 and 60. We now report disruptions in pup-induced maternal behavior in both 28 and 60 day old first generation offspring attributable to rearing condition and prenatal cocaine exposure.     

Cocaine treatment in neonatal rats affects the adult behavioral response to amphetamine

This study investigated whether exposure to cocaine during critical periods of brain development alters the motor stimulating effects of amphetamine given in adulthood. Female rats received 50 mg/kg/day cocaine HCl SC or vehicle during either postnatal days 1-10 or 11-20. At 60-65 days of age, activity counts were collected over a 15-min baseline period. Subjects then received one of 3 doses (0, 0.1, 0.25 mg/kg) of d-amphetamine sulfate SC followed by a 90-min period of activity monitoring. Adult activity in 1-10-day cocaine-treated rats was different from vehicle-treated rats in response to 0.1 mg/kg amphetamine only. Adult activity in 11-20-day cocaine-treated rats was different from vehicle-treated rats in response to 0.25 mg/kg only. The observed differences represented an increase and decrease in activity, respectively. These alterations in amphetamine response may be related to the observed alterations in D-1 receptor concentrations as well as the altered rates of brain glucose metabolism we have observed in adult rats neonatally exposed to cocaine.     

Isoxsuprine-induced changes in maternal and fetal hemodynamics and fetal electroencephalogram

Isoxsuprine has been used in obstetrics in the treatment of premature labor. Its maternal and fetal effects were studied in five ewes with dated gestations of 137 ± 1.25 days (term approximately 147 days). Isoxsuprine (1 mg/min) was infused over a 30-minute period to the anesthetized ewes while maternal and fetal blood pressures, uterine and fetal cerebral blood flows, and fetal brain function were studied. In addition, fetal and maternal acid-base values and fetal cerebral metabolism were measured at baseline, 10, 20, 30, 45, and 60 minutes. Isoxsuprine caused maternal hypotension, tachycardia, and metabolic acidosis and temporary reduction of PO₂ without affecting oxygen saturation, O₂ content, or uterine blood flow. In the fetus hypotension, tachycardia, temporary metabolic acidosis, transient reduction in PO₂ and O₂ saturation occurred while PCO₂, cerebral blood flow, brain glucose consumption, and the electroencephalogram remained essentially unchanged. Fetal pH, PO₂, and O₂ saturation returned toward baseline values at the end of the experiment.     

Relationship between fetal weight and litter size in rats: application to reproductive toxicology studies.

The inverse relationship between mammalian fetal weight and litter size has been discussed by many authors, but their opinions reveal no agreement at all. As in toxicity studies of reproduction, both parameters must be correctly evaluated. We investigated the existence of such a relationship in 2466 fetuses from 203 litters of Sprague-Dawley CD control rats. The frequency distribution of fetal weights had a normal adjustment. From the mean weight of fetuses in each litter, the mean fetal weights in each litter size and correlation coefficient were calculated and the regression line was plotted; the correlation coefficient (r = 0.677) was highly significant (P = 0.002), which made evident that there was an inverse relationship between fetal weight and litter size. If fetal weight/litter size inverse relationship is not taken into account when toxicity on the fetal weight is analyzed, wrong conclusions may be reached if the test substance reduces the litter size, provoking embryofoetal mortality. The iatrogenic decrement in fetal weight can be masked by an increment due to the litter size reduction. We suggest that in all three segments of reproductive toxicity studies, litter size must be considered as a covariate to the effect of the test substance on the fetal weight, in order to perform a correct analysis of covariance (ANCOVA), in addition to the dose factor commonly used in common ANOVA.     

The measurement of haloperidol and reduced haloperidol in neonatal hair as an index of placental transfer of maternal haloperidol

Hair samples were collected at time of delivery from three neonates and their schizophrenic mothers, who had been taking haloperidol (HP) during the perinatal period to control worsening psychotic symptoms. Maternal hair was cut into 1-cm lengths, and concentrations of HP and its major metabolite, reduced haloperidol (RHP), were measured by high-performance liquid chromatography. Neonatal hair was cut into halves, and the concentrations of HP and RHP in each half were measured. The distribution of both HP and RHP along the maternal hair paralleled the dosage of HP when hair growth was assumed to be 1 cm per month. In the upper half of hair from each of two neonates neither HP nor RHP was detected. Only HP was detected in the lower half from one, and a small peak of HP in the chromatogram was observed in the other, though under the detection limit. In the third neonate both HP and RHP were detected from both halves of hair, but the concentration of HP was larger in the lower half than in the upper. These findings suggest the possibility of monitoring the transfer of maternal HP through placenta by measuring HP and RHP concentrations in neonatal hair.     

心肌酶检测在宫内窘迫新生儿心肌损伤中的诊断价值分析

目的：探讨心肌酶检测在宫内窘迫新生儿心肌损伤中的临床价值。方法：选取宫内窘迫54例、窒息48例、宫内窘迫合并窒息45例以及正常新生儿50例,分别设为A、B、C、D组。所有患儿均于出生后24h内抽取2ml股静脉血,分别测定乳酸脱氢酶（LDH）、α-羟丁酸脱氢酶（HBDH）、肌酸激酶（CK）以及肌酸激酶同工酶（CK-MB）的血清心肌酶谱。结果：与正常对照组D组相比,A、B、C3组患儿LDH、HBDH、CK以及CK-MB均明显增高（P〈0.05）;A、B、C3组之间两两比较,心肌酶谱各项差异不明显（P〉0.05）。结论：宫内窘迫新生儿可通过检测心肌酶诊断心肌损伤,为临床及时给予营养心肌,改善心功能治疗提供参考。     

The dynamic epigenome and its implications in toxicology.

The epigenome serves as an interface between the dynamic environment and the inherited static genome. The epigenome is comprised of chromatin and a covalent modification of DNA by methylation. The epigenome is sculpted during development to shape the diversity of gene expression programs in the different cell types of the organism by a highly organized process. Epigenetic aberrations have similar consequences to genetic polymorphisms resulting in variations in gene function. Recent data suggest that the epigenome is dynamic and is therefore responsive to environmental signals not only during the critical periods in development but also later in life as well. It is postulated here that not only chemicals but also exposure to social behavior, such as maternal care, could affect the epigenome. It is proposed that exposures to different environmental agents could lead to interindividual phenotypic diversity as well as differential susceptibility to disease and behavioral pathologies. Interindividual differences in the epigenetic state could also affect susceptibility to xenobiotics. Although our current understanding of how epigenetic mechanisms impact on the toxic action of xenobiotics is very limited, it is anticipated that in the future, epigenetics will be incorporated in the assessment of the safety of chemicals.     

Cocaine exposure modulates dopamine and adenosine signaling in the fetal brain

Exposure to cocaine during the fetal period can produce significant lasting changes in the structure and function of the brain. Cocaine exerts its effects on the developing brain by blocking monoamine transporters and impairing monoamine receptor signaling. Dopamine is a major central target of cocaine. In a mouse model, we show that cocaine exposure from embryonic day 8 (E8) to E14 produces significant reduction in dopamine transporter activity, attenuation of dopamine D1-receptor function and upregulation of dopamine D2-receptor function. Cocaine's effects on the D1-receptor are at the level of protein expression as well as activity. The cocaine exposure also produces significant increases in basal cAMP levels in the striatum and cerebral cortex. The increase in the basal cAMP levels was independent of dopamine receptor activity. In contrast, blocking the adenosine A2a receptor downregulated the basal cAMP levels in the cocaine-exposed brain to physiological levels, suggesting the involvement of adenosine receptors in mediating cocaine's effects on the embryonic brain. In support of this suggestion, we found that the cocaine exposure downregulated adenosine transporter function. We also found that dopamine D2- and adenosine A2a-receptors antagonize each other's function in the embryonic brain in a manner consistent with their interactions in the mature brain. Thus, our data show that prenatal cocaine exposure produces direct effects on both the dopamine and adenosine systems. Furthermore, the dopamine D2 and adenosine A2a receptor interactions in the embryonic brain discovered in this study unveil a novel substrate for cocaine's effects on the developing brain.     

Spontaneous fetal behavior after maternal exposure to ethanol

Acute and chronic intubations of ethanol to pregnant rats produced changes in spontaneous fetal behavior four hours later. Fetuses from mothers in intermediate alcohol groups (4 and 6 g/kg) were substantially less active than controls (0 g/kg), but fetuses from low (2 g/kg) and high (8 g/kg) alcohol groups showed little indication of behavioral suppression. Circulating levels of alcohol in maternal blood, fetal homogenate and amniotic fluid at the time fetuses were observed confirmed that fetuses were exposed to alcohol in utero, but the measured concentrations of alcohol were not predictive of fetal activity. We suggest that some of the developmental consequences of Fetal Alcohol Syndrome may be the consequence of fetal inactivity induced by alcohol in utero.     

Cocaine and metabolite concentrations in the hair of South American coca chewers.

Hair samples obtained from South American Indians who were identified as daily chewers of coca leaves were analyzed by a sensitive gas chromatography/mass spectrometry (GC/MS) method for cocaine, benzoylecognine (BE), and ecognine methyl ester (EME). The mean cocaine concentration in the hair of these five subjects was 15.2 ng/mg hair +/- 11.0 (range = 1.0-28.9 ng/mg), mean BE concentration was 2.8 +/- 1.6 ng/mg hair (range = 0.3-4.4 ng/mg hair), and mean EME concentration was 1.6 +/- 1.7 (range = 0.0-4.4 ng/mg hair). The finding that cocaine was present at approximately 5 times higher concentration than BE and approximately 12 times higher than EME is surprising in light of the much longer plasma half lives of these metabolites. Washing the hair before analysis with 1% dodecyl sulfate, methanol, and distilled water reduced the concentration of cocaine in the hair but also reduced the concentrations of the metabolites. These data suggest that factors other than the drug concentration in blood may be important in determining the amount of drug incorporated into hair.