The cardiovascular effects of cocaine use in pregnancy

Stimulant Use in Pregnancy: An Under-recognized Epidemic Among Pregnant Women

Stimulant use, including cocaine, methamphetamines, ecstasy, and prescription stimulants, in pregnancy is increasingly common. In the United States, stimulants are the second most widely used and abused substances during pregnancy and pregnant women using stimulants in pregnancy are at increased risk of adverse perinatal, neonatal, and childhood outcomes. In this review, we describe the pharmacology, pathophysiology, and epidemiology of stimulants, summarize the maternal and neonatal effects of perinatal stimulant use, and outline treatment options for stimulant use disorders among pregnant women. Development of effective treatment strategies for stimulant use disorders identified among pregnant women are urgently needed.

Maternal cocaine use and cigarette smoking in pregnancy in relation to amino acid transport and fetal growth

This review covers the weight of evidence that shows the association of cocaine and cigarette smoking in pregnancy with the impaired transplacental amino acid transport which might give rise to fetal growth restriction (IUGR). Vasoconstrictive effects of both cocaine and nicotine on the placental vasculature are clearly not the only cause for inhibition of placental amino acid uptake and transfer. In vitro studies strongly suggest that cocaine decreases the activity of placental amino acid transport system A and system N, and possibly system l and system y(+), while nicotine decreases the activity of system A. These findings are supported by cordocentesis studies in human IUGR pregnancies not resulting from drug abuse. More work is needed to be done in order to understand the potential additive or synergistic effect of cocaine and cigarette smoking on fetal growth and to determine the underlying cellular mechanisms of interaction with placental amino acid transporters.

Cardiovascular effects of acute and chronic cocaine administration in pregnant and nonpregnant rabbits

The effects of cocaine administration on cardiovascular parameters were studied in anesthetized nonpregnant and pregnant rabbits with no prior exposure to cocaine and in pregnant rabbits repeatedly administered cocaine (4 mg/kg, bid, iv) for 15-20 days prior to the experiment. Rabbits were instrumented to determine the effects of cocaine on blood pressure, heart rate, and organ blood flows. Administration of the 1 and 2 mg/kg doses of cocaine increased blood pressure and decreased heart rate in both pregnant and nonpregnant rabbits. In contrast, the 4 mg/kg dose of cocaine caused reductions in both blood pressure and heart rate. Cocaine (1, 2, and 4 mg/kg, iv) also caused dose-dependent reductions in organ blood flows. Interestingly, cocaine did not affect uterine blood flow in the nonpregnant rabbits, whereas uterine and placental flows were markedly reduced in both groups of pregnant rabbits. Chronic treatment with cocaine caused a significant increase in the basal blood flow to the placenta and spleen, and a more precipitous decrease in blood flow in both organs in response to an acute injection of cocaine. The chronically treated rabbits also had a greater incidence of cardiac arrhythmias in response to an acute injection of cocaine (4 mg/kg, iv). Rabbits that received repeated administrations of cocaine experienced more prolonged reductions in blood flow than rabbits with no prior exposure to cocaine. These studies show that cocaine has marked effects on organ blood flows and that pregnancy and repeated prior administrations of cocaine can enhance these effects.

Cocaine in pregnancy. Recent data on maternal and fetal risks

Cocaine continues to be abused during pregnancy, creating increased demands on the health care system. Epidemiology and basic science research have identified and confirmed risks of adverse maternal and fetal effects when cocaine is used during pregnancy. These effects of cocaine in pregnant women often are influenced by a number of confounding variables. This article reviews those cocaine effects as well as recent data, which examine in greater detail the risks of adverse outcomes of prenatal cocaine exposure during pregnancy.

Cocaine's effects on neuroendocrine systems: clinical and preclinical studies

This review examines the effects of cocaine on the neuroendocrine system and summarizes findings from clinical studies of cocaine abusers and preclinical studies in rodents and rhesus monkeys. The effects of acute and chronic cocaine administration on anterior pituitary, gonadal, and adrenal hormones are described, and the functional consequences of chronic cocaine exposure are discussed. Many of cocaine's acute effects on the endocrine system are consistent with its actions as a monoamine reuptake inhibitor. Acute cocaine administration stimulates release of gonadotropins, ACTH, and cortisol or corticosterone and suppresses prolactin levels. It has been difficult to detect changes in basal levels of most hormones or alterations in hormone responsiveness to a challenge dose of cocaine or other agents after chronic cocaine treatment. Interpretation of clinical data is often complicated by polydrug abuse involving opiates and alcohol as well as cocaine. However, preclinical studies of the effects of chronic cocaine exposure on integrated neuroendocrine function have revealed disruptions of the estrous cycle in rats and the menstrual cycle in rhesus monkeys. Furthermore, the menstrual cycle disorders observed in rhesus monkeys parallel those reported in women who abuse cocaine. Much remains to be learned about cocaine's interactions with the endocrine system and the consequences of cocaine abuse for reproductive function.

Cocaine's lethality increases during late gestation in the rat: a study of "critical periods" of exposure

OBJECTIVE

Cocaine-associated morbidities in pregnant women (e.g., abruptio placentae, hypertension, seizures) occur mostly during the final stages of gestation. The purpose of our study was to determine whether cocaine's toxicity and blood levels varied as a function of "critical periods" of exposure during gestation.

STUDY DESIGN

To evaluate mortality rates, pregnant Long-Evans rats received subcutaneously 30, 40, or 50 mg/kg cocaine hydrochloride twice daily (C30, C40, and C50 groups) either during gestational days 7 to 13 (midgestation) or gestational days 14 to 20 (late gestation) (n 9 to 20 per group). Serum levels of the cocaine metabolite benzoylecgonine were examined in other groups of rats on either gestational day 13 (mid) or day 20 (late) in the C30 treatment condition (n = 5 and 10 per group).

RESULTS

There were no maternal mortalities in the midgestation groups at any dose. In contrast, the late-gestation groups showed a dramatic dose-dependent effect, with maternal mortality rates of 0%, 40%, and 72% in the C30, C40, and C50 groups. The late-gestation group had higher benzoylecgonine levels than the midgestation groups did.

CONCLUSIONS

Late gestation was associated with higher maternal mortality rates and higher benzoylecgonine levels, indicating that some underlying physiologic change enhanced cocaine's toxicity as pregnancy progressed. This increased sensitivity to cocaine may be mediated by estrogen or progesterone, suggesting that the cocaine-abusing woman is at increased risk for cocaine-induced morbidities whenever levels of these hormones are elevated, such as during the final stages of pregnancy or possibly when taking oral contraceptives.

Cardiovascular effects of cocaine during pregnancy

Cocaine administration during pregnancy results in major maternal cardiovascular effects that in some cases exceed those observed in the nonpregnant state. Animal studies have shown increases in heart rate and blood pressure and decreases in regional organ blood flow. Fetal effects include arterial hypoxemia, increases in blood pressure and heart rate, and increases in cerebral blood flow that may be related not only to hypertension and hypoxemia, but also to direct effects on cerebral blood vessels. Fetal intestinal blood flow is decreased. These effects may be related to the clinical consequences of cocaine use during pregnancy.

Human placenta: a direct target for cocaine action

Use of cocaine during pregnancy is known to have harmful effects on the mother and her fetus. Currently available models describing the pathogenesis of these effects focus on the involvement of cocaine target systems, primarily the noradrenaline transporter, in the mother and the fetus. The placenta which lies between the mother and the fetus is considered only as a 'silent observer' in the whole process of cocaine-induced complications during pregnancy. Recent studies have, however, shown that the placenta expresses several cocaine target proteins such as the noradrenaline transporter, the serotonin transporter, and the sigma receptor. The functions of these proteins are significantly impaired in the presence of cocaine at concentrations known to exist in the plasma of cocaine users. These studies clearly show that the placenta itself is a direct target for cocaine action and that interaction of cocaine with its target proteins in the placenta plays an important role in the pathogenesis of cocaine-induced complications in the mother and her developing fetus.

Female reproductive and developmental toxicology: overview and current approaches

In recent years, concern about possible female reproductive and developmental toxicity due to environmental contaminants, such as PCBs, has been growing. Because this area of toxicology had not been emphasized prior to this time, there are many gaps in current knowledge about female developmental and reproductive toxicology and only a limited number of validated tests to assay effects of toxicants on various parts of the reproductive and developmental cycle. This article reviews the current state of knowledge on this topic and also explores a variety of techniques for assessing female reproductive and developmental toxicity. These include an assay of the state of intercellular communication among the embryo, fetus and placenta; protocols for assessing toxicity in early pregnancy; and techniques for evaluating the role of glutathione in protecting the conceptus from xenobiotics.

Responsiveness to cocaine challenge in adult rats following prenatal exposure to cocaine

Adult rats that were gestationally exposed to cocaine and control offspring were examined for their sensitivity to challenge doses of cocaine. Offspring were derived from Sprague-Dawley dams that had received subcutaneous injections of 40 mg/kg per 3 cc cocaine hydrochloride daily on gestational days 8-20, pair-fed dams that were injected with saline, and nontreated control dams. In order to investigate the sensitivity to challenge doses of cocaine, offspring were assessed in adulthood for locomotor activity, cocaine drug discrimination, and the time course of cocaine in brain tissue following acute cocaine challenge. Adult offspring prenatally exposed to cocaine were observed to exhibit a reduced sensitivity to the discriminative stimulus effects of cocaine as evidenced by a significant shift to the right in the dose-response curve of cocaine discrimination. No prenatal treatment effects were observed in terms of the temporal patterns of cocaine discrimination or with regard to brain levels of cocaine. In addition, baseline locomotor activity and locomotor responses to challenge doses of cocaine were comparable across the prenatal treatment groups. Thus, prenatal cocaine exposure reduced sensitivity of offspring to the discriminative stimulus properties of cocaine without altering either the distribution of cocaine to the brain or the sensitivity of the offspring to the locomotor stimulant effects of cocaine.

Effects of prenatal exposure to cocaine on heart rate and nonassociative learning and retention in infant rats

Nonassociative learning and retention were assessed in terms of habituation of a heart-rate (HR) orienting response (bradycardia) to a tone in 16-day-old male and female rats prenatally exposed to cocaine and in control offspring. Offspring were derived from Sprague-Dawley dams given daily subcutaneous injections of 40 mg/kg/3 cc cocaine HCI (C40) from gestational days 8-20, pair-fed control dams given saline injections (PF), and nontreated control dams (LC). Each pup was adapted to the test apparatus for 15 min prior to being given 10 presentations of a pulsing tone, each separated by a 65-sec intertrial interval, with HR measured during a 5-sec pretone period and throughout the 10-sec tone for each trial. To assess retention, subjects were given 10 additional tone trials either 1, 2, 4, or 6 hr later. C40 male offspring displayed significantly lower basal HR following the initial 15-min isolation period than either LC or PF offspring, whereas prenatal treatment had no effect on basal HR among females. Although no differences were seen in rate of habituation, prenatal cocaine exposure was observed to affect retention of the habituated orienting response. Whereas LC and PF offspring retained habituation of the orienting response for less than 4 hr, C40 offspring exhibited no forgetting after a 4-hr interval, and showed significant loss of the habituation response only after a 6-hr interval.

Prenatal cocaine exposure affects the development of aortic adrenergic innervation and contractile responses

This study examines the effects of prenatal cocaine administration on the development of vascular sympathetic innervation and contractile responsiveness. Rabbits received cocaine (4 mg/kg, iv, bid) or saline during gestational days 8 to 29. Aortas were obtained on postnatal days 10, 20, 30 and 50. Vascular smooth muscle responsiveness was assessed by measuring aortic contractile responses to norepinephrine (NE) and to other vasoconstrictors. Vascular adrenergic innervation was evaluated by measuring desipramine sensitive [3H]-NE uptake into aortic ring segments and aortic NE content. [3H]-NE uptake and NE content were reduced at postnatal days 10 and 20 in the rabbits exposed prenatally to cocaine. Differences were not observed at postnatal days 30 or 50. The contractile response to NE was reduced in rabbits exposed to cocaine prenatally. Maximal response and potency were decreased at postnatal day 10 and potency was still decreased at day 20, but not at the older ages. Contractile responses to serotonin (5-HT) and angiotensin II (AII) were not affected by prenatal cocaine exposure. These results suggest that prenatal cocaine exposure delays the development of aortic adrenergic innervation and alpha adrenoceptor responsiveness.

Cellular mechanisms of cocaine cardiotoxicity

Although cocaine abuse has been a major drug problem in the United States for over 100 years, it has only been in the last decade that the adverse effects of cocaine on the cardiovascular system have become a serious health issue. The cardiotoxic effects of cocaine are multifactorial and remain a puzzle for investigators to solve. Evidence suggests that cocaine-induced toxic effects on the cardiac and vascular cells include both direct as well as indirect components. In addition, other chemical, physiologic, and environmental factors may further complicate and alter mechanisms and endpoints of cocaine-induced cellular toxicity. In order to fully understand the overall cardiotoxic response to cocaine, the cellular mechanisms and endpoints of toxicity of each of these potentially injurious factors must be identified.

The combined effects of cocaine and amphetamine on primary postnatal rat heart cell cultures

Recent reports demonstrated that perinatal exposure to cocaine (Coc) and amphetamines (Amph) predisposed the infant to adverse cardiovascular consequences. Dose- and time-dependent effects of Coc and Amph on postnatal rat myocardial cell cultures are described. Contractile activity, morphology, lactate dehydrogenase (LDH) release, MTT formazan production, and neutral red (NR) retention were determined. No contractile activity was observed in cultures treated with the highest drug doses. After 24 h, the percentage of areas exhibiting contractile activity was decreased in cultures exposed to the lowest doses of both drugs. When Coc and Amph were combined, beating rates were significantly altered. Morphologic alterations were observed in all treatment groups. LDH release occurred in cultures exposed to the highest doses of both drugs. No significant differences were observed for MTT or NR. These data demonstrate that Coc and Amph doses > or = 1 x 10(-5) M induce adverse effects on morphology and contractile activity of postnatal myocardial cell cultures.

Ischemia/reperfusion: a new hypothesis for the developmental toxicity of cocaine

It has been shown that multiple exposures of gravid rats to cocaine during late gestation result in significant incidences of severe malformations. Hind limb reduction defects were frequent findings in this study. Other studies have shown that comparable abnormalities can be induced in experimental animals by various procedures including vascular clamping, direct fetal exposure to epinephrine, uterine handling following laparotomy, as well as by exposure to hyperbaric oxygen. This paper reviews these and other studies, and presents a novel mechanistic hypothesis that explains their common findings. It is proposed that in each instance, conceptual hypoxia results from hypoperfusion caused by transient vasoconstriction. Following the resumption of normal perfusion, reactive oxygen species are generated by the ischemia/reperfusion mechanisms thought to underlie many pathobiologic lesions. It is proposed that the conceptus is particularly vulnerable to the toxicity of oxygen radicals because of its low antioxidant activities and the highly reduced state of its undifferentiated cells. Sensitivity to cocaine and uterine handling appears to be enhanced during late gestation and it is hypothesized that this results from changes in oxygenation and iron content that increase both the substrate and catalyst for generation of reactive oxygen species.

Studies of the role of ischemia/reperfusion and superoxide anion radical production in the teratogenicity of cocaine

The administration of multiple doses of cocaine on a single day during late gestation is teratogenic in rats in which hind limb ectrodactyly is a major finding (Webster and Brown-Woodman, '90). We have previously hypothesized that these limb malformations result from the generation of reactive oxygen species during the process of ischemia/reperfusion in vivo. In order to study the direct effects of cocaine versus the aberrant oxygenation it may induce, we have developed a system for culturing rat embryos between days 14 and 15 of gestation. Growth and development of cultured embryos are comparable to that of in vivo controls. Exposure to normoxia (95% O2) with or without cocaine failed to induce limb malformations and exposure to a single long period of hypoxia (20% O2) only reduced limb growth in the anterior-posterior axis. By contrast, embryos receiving multiple brief exposures to hypoxia developed a significant incidence of hind limb ectrodactyly that appeared indistinguishable from that induced by cocaine in vivo. By incubating day 14 embryos in a nitroblue tetrazolium derivative, 1-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), it was shown that superoxide anion radical appears in the digital rays following two episodes of reperfusion. Little reaction product was seen under the other conditions. Finally, mitochondrial electron transport particles prepared from teratogenically sensitive limb buds spontaneously "leak" electrons to form superoxide anion radical whereas those from insensitive heart fail to do so. We propose that cocaine and other exposures that can transiently reduce conceptual oxygenation during late gestation are teratogenic by virtue of their capacity to induce ischemia/reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal cocaine exposure attenuates cocaine-induced odor preference in infant rats

In order to further examine whether prenatal cocaine exposure alters the later reward efficacy of cocaine, exposed offspring were tested for cocaine-induced odor preference early in life. Test offspring were derived from Sprague-Dawley dams that received daily SC injections of 40 mg/kg/3 cc cocaine hydrochloride (C40) from gestational day 8-20, nutritional control dams receiving daily SC saline injections (NC), and nontreated control dams (LC). At testing on postnatal day 8 (P8), both LC and NC offspring were observed to exhibit a preference for the odor that had been paired on P7 with 2.0, 5.0, or 10.0 mg/kg cocaine. In contrast, C40 offspring exhibited a significant odor preference only when the odor had been previously paired with 5.0 or 10.0 mg/kg cocaine. These results, combined with previous work from our laboratory showing that adult offspring exposed gestationally to cocaine did not exhibit a cocaine-induced conditioned place preference, provide evidence that offspring exposed prenatally to cocaine are less likely to develop a preference for stimuli associated with cocaine. Further studies are needed to determine whether these alterations in cocaine preference reflect a learning deficit, pharmacokinetics factors, or an attenuation in the rewarding properties of cocaine.

A primary culture system of postnatal rat heart cells for the study of cocaine and methamphetamine toxicity

It is now well documented that both cocaine (Coc) and methamphetamine (Meth) are independently capable of inducing injurious effects on the adult and developing myocardium. In addition, when these drugs are used concomitantly such as in polydrug abuse, it has been suggested that they may cause synergistic adverse effects on the myocardium. In this investigation, primary myocardial cell cultures were established from 3-5-day-old Sprague-Dawley rats to describe the adverse effects of Coc and Meth on the myocardium. After the cells were in culture for 4 days, they were exposed to 1 x 10(-5) and 1 x 10(-3) M Coc alone; 1 x 10(-5) and 1 x 10(-3) M Meth alone; and combinations of 1 x 10(-3) M Coc with 1 x 10(-5) M Meth and 1 x 10(-5) M Coc with 1 x 10(-5) M Meth. Lactate dehydrogenase (LDH) release, morphology, and beating activity were evaluated after exposure to the drugs for 1, 4 and 24 h. With all treatment groups for the first 4 h, LDH release was not significantly different from untreated controls. Significant LDH release (P less than 0.001) was exhibited at 24 h with 1 x 10(-3) M Coc alone, 1 x 10(-3) M Meth alone, and 1 x 10(-3) M Coc with 1 x 10(-5) M Meth. For 24 h of treatment, cellular injury (pseudopodia, vacuolization, granulation) induced by 1 x 10(-3) M and 1 x 10(-5) M Coc alone was extensive and minimal, respectively. When 1 x 10(-5) M Meth was added with 1 x 10(-5) M Coc, pseudopodia formation was extensive. No measurable beating activity was observed at 1, 4 and 24 h exposure to 1 x 10(-3) M Coc alone and 1 x 10(-3) M Coc with 1 x 10(-5) M Meth. At 1 h, beating activity after treatment with 1 x 10(-5) M Coc alone and 1 x 10(-5) M Meth alone was not significantly different from untreated controls; however, the percentage of areas exhibiting contractile activity was depressed. Addition of Meth (1 x 10(-5) M) potentiated Coc-induced (1 x 10(-5) M) depression of contractile activity at all 3 time-points. These data suggest that Coc and Meth may interact synergistically at the cellular level to directly potentiate injury to postnatal myocardial cell cultures.