Neurobehavioral and immunological effects of prenatal cocaine exposure in rat

Neuroendocrine and immune pathways from pre- and perinatal stress to substance abuse

Early life adversity is a documented risk factor for substance abuse and addiction. The pre- and perinatal period (i.e., from implantation, through pregnancy, to 6 months of age) is a critical period marked by high biological plasticity and vulnerability, making perinatal stress a particularly robust form of adversity. The neuroendocrine and immune systems are key mechanisms implicated in the transmission of addiction risk. We review animal and human studies that provide preliminary evidence for links between perinatal stress, neuroendocrine and immune dysregulation, and risk for substance abuse and addiction. A translational neuroscience perspective is employed to elucidate pre- and perinatally-induced biological mechanisms linked to addiction and discuss implications for prevention and intervention efforts. Significant evidence supports associations between pre- and perinatal stress and dysregulation of the hypothalamic-pituitary-adrenal axis and immune systems as well as links between neuroendocrine/immune functioning and addiction risk. More work is needed to explicitly examine the interplay between pre- and perinatal stress and neuroendocrine/immune disruptions that together heighten substance abuse risk. Future work is needed to fully understand how pre- and perinatal stress induces biological alterations to predispose individuals to higher risk for addiction. Such knowledge will strengthen theoretically-driven and empirically-supported prevention efforts for substance abuse and addiction.

Evidence for an immune signature of prenatal alcohol exposure in female rats

Evidence for immune/neuroimmune disturbances as a possible root cause of a range of disorders, including neurodevelopmental disorders, is growing. Although prenatal alcohol exposure (PAE) impacts immune function, few studies to date have examined immune function in relation to long-term negative health outcomes following PAE, and most have focused on males. To fill this gap, we utilized a rat model to examine the effects of PAE on immune/neuroimmune function during early-life [postnatal day 1 (P1), P8, and P22] in PAE and control females. Due to the extensive interplay between the immune and endocrine systems, we also measured levels of corticosterone and corticosterone binding globulin (CBG). While corticosterone levels were not different among groups, CBG levels were lower in PAE offspring from P1 to P8, suggesting a lower corticosterone reservoir that may underlie susceptibility to inflammation. Spleen weights were increased in PAE rats on P22, a marker of altered immune function. Moreover, we detected a unique cytokine profile in PAE compared to control offspring on P8 - higher levels in the PFC and hippocampus, and lower levels in the hypothalamus and spleen. The finding of a specific immune signature in PAE offspring during a sensitive developmental period has important implications for understanding the basis of long-term immune alterations and health outcomes in children with Fetal Alcohol Spectrum Disorder (FASD). Our findings also highlight the future possibility that immune-based intervention strategies could be considered as an adjunctive novel therapeutic approach for individuals with FASD.

Cocaine-induced neurodevelopmental deficits and underlying mechanisms

Exposure to drugs early in life has complex and long-lasting implications for brain structure and function. This review summarizes work to date on the immediate and long-term effects of prenatal exposure to cocaine. In utero cocaine exposure produces disruptions in brain monoamines, particularly dopamine, during sensitive periods of brain development, and leads to permanent changes in specific brain circuits, molecules, and behavior. Here, we integrate clinical studies and significance with mechanistic preclinical studies, to define our current knowledge base and identify gaps for future investigation. Birth Defects Research (Part C) 108:147-173, 2016. © 2016 Wiley Periodicals, Inc.

Prenatal cocaine exposure and trajectories of externalizing behavior problems in early childhood: examining the role of maternal negative affect

This study examined the association between prenatal cocaine exposure (PCE) and developmental trajectories of externalizing behavior problems from 18 to 54 months of child age. A hypothesized indirect association between PCE and externalizing trajectories via maternal negative affect was also examined. Caregiving environmental risk and child sex were evaluated as moderators. This study consisted of 196 mother-child dyads recruited at delivery from local area hospitals (107 PCE, 89 non-PCE) and assessed at seven time points across the toddler to preschool periods. Results revealed no direct associations between PCE and externalizing behavior problem trajectories. However, results did indicate that PCE shared a significant indirect relationship with externalizing behavior problem trajectories via higher levels of maternal negative affect. The association between PCE and externalizing problem trajectories was also moderated by caregiving environmental risk such that PCE children in high-risk caregiving environments did not experience the well-documented normative decline in externalizing behavior problems beginning at around 3 years of age. This study suggests potential pathways to externalizing behavior problems among high-risk children.

Empathic responsivity at 3 years of age in a sample of cocaine-exposed children

This study examined the association between prenatal exposure to cocaine and behavioral and physiological responsivity. Participants were 216 mother-infant dyads (116 cocaine exposed-CE, 100 nonexposed-NCE) recruited at birth. Measures of heart rate (HR) and respiratory sinus arrhythmia (RSA) were obtained during baseline and during a task designed to elicit empathy (exposure to infant crying). When the effects of prenatal cocaine use were examined in the context of polydrug use, results of model testing indicated that lower gestational age, prenatal exposure to cocaine and postnatal exposure to alcohol were each associated with a reduced suppression of RSA during the empathy task. These findings provide additional support for an association between prenatal cocaine exposure and dysregulation during early childhood during affect-eliciting environmental challenges.

Drugs in pregnancy: the effects on mother and her progeny

Drug abuse during pregnancy is a growing problem in all developed countries all over the world. The drugs easily cross the placental barrier into the fetal body and are present also in the maternal milk. Therefore, it may affect the development of the child pre- as well as postnatally. The effects of prenatal drug exposure are long-lasting and persist until adulthood. The present review summarizes the clinical and experimental evidence showing how opioids and psychostimulants can affect maternal behavior of drug-abusing mother and the development of their offspring.

Cocaine Exposure and Children's Self-Regulation: Indirect Association via Maternal Harshness

OBJECTIVES

This study examined the association between prenatal cocaine exposure and children's self-regulation at 3 years of child age. In addition to direct effects of prenatal cocaine exposure on children's self-regulation, we hypothesized there would be indirect associations between cocaine exposure and self-regulation via higher maternal harshness and poor autonomic regulation in infancy.

METHODS

The sample consisted of 216 mother-infant dyads recruited at delivery from local area hospitals (116 cocaine-exposed, 100 non-exposed). Infant autonomic regulation was measured at 7 months of age during an anger/frustration task, maternal harshness was coded from observations of mother-toddler interactions at 2 years of age, and children's self-regulation was measured at 3 years of age using several laboratory paradigms.

RESULTS

Contrary to hypotheses, there were no direct associations between maternal cocaine use during pregnancy and children's self-regulation. However, results from testing our conceptual model including the indirect effects via maternal harshness or infant parasympathetic regulation indicated that this model fit the data well, χ(2) (23) = 34.36, p > 0.05, Comparative Fit Index = 0.95, RMSEA = 0.05. Cocaine using mothers displayed higher intensity of harshness toward their toddlers during lab interactions across a variety of tasks at 2 years of age (β = 0.23, p < 0.05), and higher intensity of harshness at 2 years was predictive of lower self-regulation at 3 years (β = -0.36, p < 0.01). Maternal cocaine use was also predictive of a non-adaptive increase in respiratory sinus arrhythmia (RSA) from baseline to the negative affect task, but RSA change in infancy was not predictive of self-regulation at 3 years.

CONCLUSION

RESULTS are supportive of animal models indicating higher aggression among cocaine treated dams, and indicate that higher maternal harshness among cocaine using mothers is predictive of child self-regulatory outcomes in the preschool period.

Social behavior of offspring following prenatal cocaine exposure in rodents: a comparison with prenatal alcohol

Clinical and experimental reports suggest that prenatal cocaine exposure (PCE) alters the offsprings' social interactions with caregivers and conspecifics. Children exposed to prenatal cocaine show deficits in caregiver attachment and play behavior. In animal models, a developmental pattern of effects that range from deficits in play and social interaction during adolescence, to aggressive reactions during competition in adulthood is seen. This review will focus primarily on the effects of PCE on social behaviors involving conspecifics in animal models. Social relationships are critical to the developing organism; maternally directed interactions are necessary for initial survival. Juvenile rats deprived of play behavior, one of the earliest forms of non-mother directed social behaviors in rodents, show deficits in learning tasks and sexual competence. Social behavior is inherently complex. Because the emergence of appropriate social skills involves the interplay between various conceptual and biological facets of behavior and social information, it may be a particularly sensitive measure of prenatal insult. The social behavior surveyed include social interactions, play behavior/fighting, scent marking, and aggressive behavior in the offspring, as well as aspects of maternal behavior. The goal is to determine if there is a consensus of results in the literature with respect to PCE and social behaviors, and to discuss discrepant findings in terms of exposure models, the paradigms, and dependent variables, as well as housing conditions, and the sex and age of the offspring at testing. As there is increasing evidence that deficits in social behavior may be sequelae of developmental exposure alcohol, we compare changes in social behaviors reported for prenatal alcohol with those reported for prenatal cocaine. Shortcomings in the both literatures are identified and addressed in an effort to improve the translational value of future experimentation.

Potential latent effects of prenatal cocaine exposure on growth and the risk of cardiovascular and metabolic disease in childhood

The literature strongly suggests that prenatal exposure to certain medications and substances does not cause major malformations in early childhood. However, these exposures may have far-reaching latent health effects, such as restricted growth, hypertension, and cardiovascular events in adulthood. We reviewed the literature to identify the effects of prenatal cocaine exposure on growth and the risk of cardiovascular and metabolic disease in late adolescence and early adulthood by examining studies that were published in peer-reviewed English-language journals from 1990 through 2009 and indexed in MEDLINE. We found that animal and clinical studies of the influence of prenatal cocaine exposure on child and adolescent growth and the subsequent development of myocardial and cardiometabolic disease risk factors are few and inconclusive. Studies support the hypothesis that vascular and hemodynamic functions are partially programmed in early life and thus substantially influence vascular aging and arterial stiffening in later life. Sub-optimal fetal nutrition and growth may increase blood pressure and the development of cardiovascular and metabolic disease in late life. How prenatal cocaine and other drug exposure effects this relationship is currently unknown. Despite high rates of cocaine and other drug use during pregnancy (up to 18% in some studies), little is known about the health effects of prenatal cocaine exposure in adolescence and early adulthood. The few studies of early growth deficits persisting into adolescence are inconclusive. The literature provides little information on how exposed children grow into adulthood and about their subsequent risk of cardiometabolic and vascular disease.

The medial preoptic area is necessary for motivated choice of pup- over cocaine-associated environments by early postpartum rats

Converging evidence suggests that the motivation to seek cocaine during the postpartum period is significantly impacted by the competing incentives of offspring, a stimulus unique to this life stage. In the present study, the functional role of the medial preoptic area (mPOA), a critical site involved in maternal responsiveness, on processing incentive value of pup-associated cues and influencing response allocation for pup- over cocaine-associated environments was investigated using a concurrent pup/cocaine choice conditioned place preference (CPP) paradigm. Early postpartum females with bilateral guide cannulae aimed into the mPOA or into anatomical control sites were conditioned, from postpartum days (PPD) 4 to 7, to associate different uniquely featured environments with pups or cocaine. CPP was tested on PPD8 following intra-mPOA infusions of either 2% bupivacaine or saline vehicle. In two additional experiments, the effects of intra-mPOA infusions of bupivacaine on expression of conditioned responding induced by environments associated with either pups or cocaine were examined separately. Transient inactivation of the mPOA selectively blocked the conditioned preferences for pup-associated environments, significantly contrasting the robust pup-CPP found in non-surgical and intra-mPOA vehicle-treated females. In contrast, mPOA inactivation failed to alter cocaine-CPP in postpartum females. When given a choice between environments associated with pups or cocaine, transient functional inactivation of the mPOA altered choice behavior, biasing the preference of females toward cocaine-associated environments, such that almost all preferred cocaine- and none the pup-associated option. The anatomical specificity was revealed when inactivation of adjacent regions to the mPOA did not affect CPP responses for pups. The findings support a critical role for the mPOA in mediating pup-seeking behavior, and further suggest that the competing properties of pups over alternative incentives, including drugs of abuse, rely on mPOA integrity to provide relevant pup-related information to the circuitry underlying the choice behavior between pups and alternative stimuli.

Prenatal exposure to cocaine alters the development of conditioned place-preference to cocaine in adult mice

As addiction is increasingly formulated as a developmental disorder, identifying how early developmental exposures influence later responses to drugs of abuse is important to our understanding of substance abuse neurobiology. We have previously identified behavioral changes in adult mice following gestational exposure to cocaine that differ when assessed with methods employing contingent and non-contingent drug administration. We sought to clarify this distinction using a Pavlovian behavioral measure, conditioned place-preference. Adult mice exposed to cocaine in utero (40 or 20 mg/kg/day), vehicle and pair-fed controls were place-conditioned to either cocaine (5 mg/kg or 20 mg/kg, i.p.) or saline injections. The development of conditioned place-preference to cocaine was impaired in mice exposed to cocaine in utero, and was abolished by fetal malnutrition. A context-specific place-aversion to vehicle but not cocaine injection was observed in prenatally cocaine-exposed mice. Locomotor behavior did not differ among prenatal treatment groups. We conclude that early developmental exposure to cocaine may diminish the subsequent rewarding effects of cocaine in adulthood measured with classical conditioning techniques, and that this is not due to changes in locomotor behavior. Sensitivity to acute stress is also altered by prenatal cocaine exposure, consistent with earlier findings in this model.

Gestational exposure to cocaine alters cocaine reward

Exposure of the developing foetus to drugs of abuse during pregnancy may lead to persistent abnormalities of brain systems involved in drug addiction. Mice prenatally exposed to cocaine (25 mg/kg), physiological saline or non-treated during the last 7 days of pregnancy were evaluated in adulthood for the rewarding properties of cocaine (3, 25 and 50 mg/kg), using the conditioned place preference procedure. Dams treated with physiological saline gained significantly less weight over the course of gestation than controls; no other differences were observed in the maternal and offspring data. All the animals developed preference to 3 and 25 mg/kg of cocaine, but those treated prenatally with cocaine did not develop preference after receiving the highest cocaine dose. In these mice, the motor activity in response to 50 mg/kg showed a small decrease. Although a reduced response to the highest cocaine dose can be argued, we suggest that the lack of preference obtained is more likely attributable to an increased sensitivity to the environmental cues associated during training to an aversive effect of this cocaine dose. The aversive properties of cocaine seem to be more apparent and to prevail over the rewarding action of the highest dose in exposed animals. These findings indicate that recurrent gestational cocaine exposure results in permanent (mal)adaptations of the structure and function of brain reward systems.

Prenatal cocaine and morphine alter brain cyclin-dependent kinase 5 (Cdk5) activity in rat pups

Pregnant rats received daily injections of saline, cocaine (20 mg/kg), morphine (2 mg/kg), or the combination of both drugs, on days 13-20 of gestation. Cyclin-dependent kinase 5 (Cdk5) activity was then measured in the resulting pups on postnatal days 1, 7, 14 and 28. Cocaine resulted in a time dependent increase in brain Cdk5 activity which peaked on day 14. Morphine, in contrast, induced a decrease in Cdk5 activity which was also maximal on day 14. Combined administration of the two drugs led to smaller increases than those seen after cocaine alone. These findings demonstrate that prenatal drug exposure can modify postnatal activity of Cdk5 in the brain and raise the possibility that alterations in Cdk5 may play a role in some of the neural and behavioral effects produced by these treatments.

Prenatal cocaine dampened behavioral responses to methylphenidate in male and female adolescent rats

Clinical and animal data point toward deficits in attention and arousal after prenatal cocaine exposure. Since methylphenidate (MPD) is widely used to treat attention disorders, we wanted to determine whether prenatal cocaine (PC) exposure affects the behavioral response to MPD in young rats of both sexes. Pregnant dams received 60 mg/kg of cocaine or vehicle from gestational days 8-22 by intragastric intubations. After delivery, litters were culled to 10 (5 males, 5 females) and fostered. On a single day between PND 41-44 locomotion was recorded in a Plexiglas box within an Accuscan activity monitor after receiving a single injection of 10 mg/kg intraperitoneally of MPD or saline. Rats were also videotaped for analysis of stereotyped behavior. Results showed that MPD administration enhanced locomotion compared to saline injected groups. PC exposure in male rats did not have any effect on the locomotor response to MPD compared to prenatal controls. However, PC-exposed males showed a lower amount of time spent in low intensity stereotypy compared to prenatal control males and both groups of females that received MPD. PC exposure in female rats that received MPD dampened the locomotor response compared to prenatal control females that also received MPD. In conclusion PC exposure dampens the behavioral response to MPD differentially in males and females with an apparent selectivity of locomotion in females and stereotyped behavior in males.

Level of prenatal cocaine exposure and 48-month IQ: importance of preschool enrichment

OBJECTIVE

This analysis was designed to determine whether prenatal cocaine exposure is related to children's standardized cognitive test scores at age 4 years after control for relevant covariates.

METHODS

Masked examiners using the WPPSI-R assessed ninety-one 4-year-old children with prenatal cocaine exposure and 79 children of comparable demographic background who were not exposed. Level of cocaine exposure was documented by postpartum interviews of mothers and assays of the infants' meconium.

RESULTS

Prenatal cocaine exposure, analyzed as exposed/unexposed or as an ordinal dose variable, was not associated in bivariate or multivariate models with decrements in full-scale IQ, performance IQ, verbal IQ, or in any of the subtests. In bivariate analyses, we found significant differences between exposure groups defined as "unexposed", "lighter", and "heavier" in mean scores of the WPPSI-R subtests Object Assembly (P=0.04) and Picture Completion (P=0.03). For these scores, children with heavier exposure attained higher scaled scores. Birth mother's education and child's experience with preschool enrichment were both associated with higher verbal IQ scores.

CONCLUSION

These findings suggest that prenatal cocaine exposure does not exert negative effects on the cognitive competence of preschool-aged children. Children with a history of prenatal cocaine exposure benefit from preschool programs that have been shown to enhance outcomes for other low-income children.

Prenatal exposure to cocaine decreases adenylyl cyclase activity in embryonic mouse striatum

Adenylyl cyclase activity was measured in the striatum of naive mice as a function of age and in mice exposed in utero to cocaine. In naive Swiss-Webster mice, basal and forskolin-stimulated adenylyl cyclase activity increased gradually from embryonic day 13 (E13) until 2-3 weeks of age when activity peaked before decreasing slightly to adult levels. The ability of the dopamine D1 receptor agonist, SKF 82958, to stimulate adenylyl cyclase activity also increased in magnitude until P15. In a separate study, pregnant Swiss-Webster mice were injected twice daily with cocaine (15 mg/kg, s.c.) or an equal volume of saline from E10 to E17. Adenylyl cyclase activity was measured in the striatum of E18 embryos. Basal adenylyl cyclase activity was significantly reduced following prenatal exposure to cocaine. Likewise, the ability of forskolin or SKF 82958 to stimulate adenylyl cyclase was attenuated following cocaine exposure. DeltaFosB was not induced, contrary to what is seen in adult mice. These results demonstrate a functional change in a critical signal transduction pathway following chronic in utero exposure to cocaine that might have profound effects of the development of the brain. Alterations in the cAMP system may underlie some of the deficits seen in humans exposed in utero to cocaine.

Does drug abuse beget drug abuse? Behavioral analysis of addiction liability in animal models of prenatal drug exposure

Prenatal exposure to drugs of abuse is the single largest preventable cause of developmental compromise of American children today. In the clinical population, it is difficult to determine the independent effects of gestational exposure to a single drug on brain development, in part due to the confounding effects of additional risk factors that are encountered in the substance-abusing population. The enormous clinical and societal problem of gestational toxicity of drugs of abuse, both legal and illegal, has driven the need to develop and investigate animal models of gestational drug exposure in which these variables can be controlled. More specifically, as clinical data are gathered suggesting an increased liability to substance abuse among children of drug-abusing mothers, a mechanistic understanding of the lasting effects of early drug exposure on the developing brain and the behavioral repertoire of the developing animal is crucial. In this review we summarize experimental animal research that investigates the role of drug exposure in utero on the functional development of specific brain circuits that are involved in the reinforcing effects of drugs of abuse, and on the behaviors that are mediated by these brain reward systems.

Immunomodulation by cocaine and ketamine in postnatal rats

The abuse of cocaine (COC) in combination with ketamine (KET) among pregnant women was shown to be high. Transplacental exposure is not the only route by which a newborn may be exposed to these agents, but they can also distribute into breast milk. Chronic COC exposure is associated with immunological modulation in human and animal models. The effect of sub-chronic exposure to COC and KET alone and in combination on the developing immune system was assessed in neonatal male Sprague-Dawley (SD) rats. To simulate the route of exposure during lactation, newborn male rats were treated orally with saline, COC alone (20 mg/kg), KET alone (50 mg/kg), or KET (50 mg/kg) followed 15 min later by COC (20 mg/kg) from days 1 to 21 of life. Pups were sacrificed 30 min following the last treatment. Total circulating leukocyte and lymphocyte counts were decreased with relative neutrophilia, while spleen/body weight ratio and IgM antibody response to sheep red blood cells (SRBCs) were increased in animals treated with COC. Moreover, treatment with COC alone increased serum interleukin 10 (IL-10) concentration; however, it did not affect serum interferon gamma (IFN-gamma) concentration. On the other hand, KET treatment did not produce any significant change of any of these parameters. However, when co-administered with COC, the immunomodulatory effects of COC were prevented. COC caused a significant increase in serum corticosterone concentration that KET effectively prevented. Lack of significant change of plasma and tissue concentrations of norcocaine (NC) suggested no role for COC metabolism in COC-induced immunomodulation. However, the results of this study indicate that COC-induced immunomodulatory reactions and their prevention by KET most likely occurred through neuroendocrinal mechanisms.

Prenatal cocaine and/or nicotine exposure produces depression and anxiety in aging rats

The adult use of cocaine and nicotine has been linked to depression and/or anxiety. Changes in emotional behavior were assessed using behavioral paradigms developed as animal analogs of psychiatric disorders in 12-14 month old Sprague-Dawley rats exposed daily on gestational days 8-20 to cocaine and nicotine, either alone or in combination. Results from the elevated plus maze (EPM), used to assess anxiety-related behaviors, indicated that offspring prenatally exposed to either high-dose cocaine (40 mg/kg/day) or high-dose nicotine (5.0 mg/kg/day) were less timid/more impulsive. Animals from these two groups spent the most time on the open arms, and had the highest percentage of entries into the open arms of the EPM. Combined in utero exposure to cocaine and nicotine nullified these effects. Cocaine challenge (20 mg/kg) did not interact with prenatal treatment, but increased activity on all arms of the EPM in all groups. Sucrose preference was used as a measure of anhedonia, a cardinal symptom of depressive illness. Reduced sucrose preference was seen only in the group of offspring prenatally exposed to high-dose cocaine (40 mg/kg) plus low-dose nicotine (2.5 mg/kg/day). Exposure to a water-deprivation stress normalized sucrose preference in this group, without altering preference or intake in the other prenatal treatment groups. Transient hyperactivity was seen in the offspring of dams treated with high-dose nicotine, an effect that was again reversed in combined drug groups. Traditional gender differences in activity levels and sucrose intake, that is, females greater than males, were still evident in this population of aging rats. These data indicate that prenatal exposure to cocaine and/or nicotine has long-term effects on emotional behavior. Combined drug exposure contributed to the development of depressive symptoms, but not anxiety-like behavior, in a dose-dependent manner. In contrast, exposure to high doses of either drug alone reduced cautionary behavior. Data from this line of research could provide insight into the pathogenesis of emotional disorders, especially during the aging process.

Neonatal hair analysis for benzoylecgonine: a sensitive and semiquantitative biological marker for chronic gestational cocaine exposure

Hair analysis for the major metabolite of cocaine, benzoylecgonine (BZE) was performed in a cohort of 251 predominantly African-American newborns utilizing a modified radioimmunoassay (RIA) (Abuscreen Roche Laboratories, Nutley, N.J., USA). Maternal drug intake was confirmed by positive urine drug screen for cocaine metabolites at the time of delivery. The BZE concentrations reported here are the composites of both the parent compound cocaine (hydrolyzed to BZE) and the native BZE metabolized by the patient and deposited in the hair follicle. Hair analysis as an indicator for gestational cocaine exposure had a sensitivity of 88%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 85%. The range of BZE was 99-23,300 ng/g of hair, with 79% having hair BZE levels <5,000 ng/g of hair. The BZE RIA was confirmed by gas chromatography and mass spectrometry (GC/MS). Of the 18 mother/infant pairs tested, the hair BZE ratio (maternal to neonatal) varied from 0.5 to 8.9 in 13 pairs. In spite of maternal high hair BZE levels, 5 newborns had no evidence of hair BZE, stressing the importance of the placental role for the cocaine transfer to the fetus. After controlling for gestational age, higher BZE levels significantly correlated with smaller head circumference (p < 0.03) and birth weight (p < 0.01).

Embryonic "binge" cocaine exposure alters neural-immune and neural-endocrine interactions in young chickens: involvement of serotonin(2) receptors

As part of our characterization of the developmental consequences of prenatal cocaine exposure, cocaine was injected into eggs containing viable chicken embryos on embryonic day (E) 18 and the fever response to the endotoxin lipopolysaccharide (LPS) and a delayed-type hypersensitivity response to phytohemagglutinin (PHA) were assessed postnatally. E18 cocaine exposure did not affect basal body temperature. LPS induced a fever in the chicks at 4 h post-injection on post-hatch day (D) 4 and 2 h post-injection on D24. E18 cocaine exposure suppressed the peak LPS-induced fever by 50% at both ages. E18 cocaine exposure also suppressed the hypersensitivity reaction to an intradermal injection of PHA on D17, while having no effect on the response to a saline injection. To determine the importance of serotonin(2) (5-HT(2)) receptors in the developmental toxicity of cocaine, varying doses of the 5-HT(2) antagonist ritanserin were injected on E17 followed by cocaine on E18. Ritanserin, like cocaine, did not alter basal temperature, but it dose-relatedly attenuated or blocked cocaine's effect on LPS-induced fever on both D4 and D24. Ritanserin pretreatment was also able to block the blunted isolation stress response seen in D16 chicks following E18 cocaine exposure. Thus, late prenatal cocaine exposure significantly alters adaptive fever and hypersensitivity responses, and embryonic 5-HT(2) receptors played a mediating role in the fever effect.

Attenuation of cocaine-induced genomic and functional responses in prenatal cocaine-exposed rabbits

The effects of in utero cocaine exposure on cocaine-induced genomic and functional responses in postnatal life were examined. Pregnant Dutch Belted rabbits were injected intravenously, twice daily, with cocaine hydrochloride (4 mg/kg) or saline from day 8 through day 29 of pregnancy. Prenatally exposed kits were challenged with cocaine on postnatal day 20. In prenatal saline-exposed kits, cocaine induced time- and dose-dependent c-fos gene expression in both frontal cortex and striatum. Prenatal cocaine exposure reduced cocaine-induced c-fos responses by 35-58% in the frontal cortex and 37-41% in the striatum. Cocaine-induced functional responses that included head bobbing, seizure, and locomotor activity were also attenuated in prenatal cocaine-exposed kits. Cocaine-induced c-fos expression and functional responses were blocked by the D(1) dopamine receptor antagonist, SCH23390, or by the serotonin receptor antagonist, methysergide, but not by the D(2) dopamine receptor antagonist, L-sulpride. The results indicate that in utero cocaine exposure leads to diminished responses to cocaine challenge in the offspring, which may be mediated by prenatal cocaine-induced alterations in one or more components of the D(1) dopamine and/or serotonin receptor signaling systems during early postnatal life.

The search for congenital malformations in newborns with fetal cocaine exposure

CONTEXT

The association between prenatal cocaine exposure and congenital anomalies is not definitive.

OBJECTIVE

To determine whether prenatal cocaine exposure results in an increased number or identifiable pattern of abnormalities.

DESIGN

A prospective, longitudinal cohort enrolled between 1991 and 1993.

SETTING

Rural public health population delivering at a regional tertiary medical center.

PATIENTS

Two hundred seventy-two offspring of 154 prenatally identified crack/cocaine users and 154 nonusing controls were matched on race, parity, location of prenatal care (that related to level of pregnancy risk), and socioeconomic status. Drug use was determined through repeated in-depth histories and urine screens. Infants not examined within 7 days of birth were excluded.

OUTCOME MEASURES

Assessments were made by experienced examiners masked to maternal drug history. Included were 16 anthropometric measurements and a checklist of 180 physical features defined and agreed upon in advance.

RESULTS

There were no differences on major risk variables between the included and excluded infants. There were significantly more premature infants in the cocaine-exposed group. Cocaine-exposed infants were significantly smaller in birth weight, length, and head circumference but did not differ on remaining anthropometric measurements. There was no difference in type or number of abnormalities identified between the exposed and nonexposed groups. There was no relationship between amount or timing of exposure and any of the outcomes.

CONCLUSIONS

This prospective, large-scale, blinded, systematic evaluation for congenital anomalies in prenatally cocaine-exposed children did not identify an increased number or consistent pattern of abnormalities.

Gestational exposure to cocaine or pharmacologically related compounds: effects on behavior and striatal dopamine receptors

Gestational cocaine (COC) exposure has been reported to alter behavior and possibly dopamine (DA) receptors. In this paper, we further examined the effects of prenatal COC (40 mg/kg, s.c.) on DA receptor binding and the behavioral response to quinpirole, a DA D2 receptor agonist. In an attempt to elucidate possible mechanisms of such effects, we exposed pregnant dams to specific reuptake blockers; fluoxetine 12.5 mg/kg, a serotonin reuptake blocker; desipramine 10 mg/kg, a norepinephrine reuptake blocker; GBR-12909 10 mg/kg, a DA reuptake blocker; or to a local anesthetic, lidocaine 40 mg/kg. Drugs were administered once daily over gestational days 8-20. Control dams were injected with saline (SAL) or pair-fed to the COC group. Quinpirole challenge was performed in the offspring on post natal day 19. Two pups per litter were injected (s.c.) with 0.03 or 0.09 mg/kg quinpirole-HCl on post-natal day 19. The remaining pups in each litter were sacrificed for analysis of striatal DA receptors. Results showed that only COC exposure altered the behavioral response to the quinpirole challenge by increasing quinpirole-induced stereotypy and motor activity relative to SAL controls. DA receptor analysis showed no alteration in K(D) or B(MAX) for striatal D1 or D2 sites in any group. These results suggest that prenatal COC exposure produces alterations in function of the D2 receptor complex which are not reflected in K(D) or B(MAX) and that these effects are not fully mimicked by exposure to specific monoamine reuptake blockers or a local anesthetic.

Altered responsiveness to stress and NMDA following prenatal exposure to cocaine

Pregnant Sprague--Dawley rats were treated once daily with 40-mg/kg cocaine or saline from gestation days (GD) 12 to 21. A third group of pregnant dams was used as a pairfed control. Male and female offspring were examined for stress endurance response as determined by the cold-water swim test on postnatal days (PND) 21, 30, 40, and 60. Male and female offspring exposed to cocaine in utero were found to have diminished tolerance and altered hormonal response to stress. Moreover, prenatal cocaine exposure has been associated with significant increases in severity of N-methyl-D-aspartate (NMDA; 35 mg/kg) behavioral responses (tail twitches, wetdog shaking, and convulsion) as compared to control. Examining the experimental groups for pain sensitivity using the tail-flick and the hot-plate methods indicated that prenatal cocaine exposure altered pain sensitivity. NMDA receptor binding studies showed an increase in receptor density in the hippocampus and hypothalamus of the cocaine-treated group. These results indicate that gestational cocaine exposure is associated with long-term alterations in response to stress, NMDA receptor, and pain sensitivity in the rat offspring.

The effects of prenatal cocaine exposure and genotype on the ultrasonic calls of infant mice

Estimates are that as many as 44,000 humans are exposed to cocaine in utero per year. In this study we examined the effects of prenatal cocaine exposure on one aspect of the mother-infant relationship in mice, infant ultrasonic calls. We mated C57BL/10J female mice with males of three different inbred strains (producing pups of three different F(1) genotypes). We injected those females, subcutaneously, with saline or 20 mg/kg of cocaine hydrochloride on days 7-17 of gestation. That dosage did not compromise mother or pup viability, weight, or gestation length. On postnatal days 2-4, we recorded and measured the calls of pups while they were separated from their nest and slightly chilled. The results indicate changes in the ultrasonic calls as a function of cocaine and genotype. Overall, cocaine reduced the number of calls and increased the beginning pitch of calls. Pups of one genotype, a C57BL/10JxSJL/J hybrid were unaffected by cocaine exposure. The effects of cocaine, though reliable, were small, explaining only 1-2% of the total sum of squares. The size of the effect is in part due to the differential effect of cocaine on different genotypes.

Adolescent cocaine and injection stress effects on the estrous cycle

Chronic cocaine exposure during critical periods of development induces short- and long-term effects. During the pubertal period, the hypothalamic-pituitary-gonadal (HPG) axis undergoes many dynamic changes. The present study investigated whether chronic periadolescent cocaine alters reproductive maturity in the rat. Sixty female Long-Evans hooded rats were randomly assigned to one of three conditions (20 mg cocaine/kg/day, saline injected and uninjected), for dosing from postnatal day 21 (P21) through P60. Several indicators of reproductive maturation and functioning were assessed during and following treatment. Cocaine exposure had no effect on the onset of puberty or on the date of first ovulation. The number of proestrus-estrus transitions was significantly lower in cocaine-exposed females compared to uninjected females, but not compared to saline-injected controls. This reduction was observed during exposure to cocaine, as well as after the cessation of injections. During the dosing period, cocaine-exposed rats also exhibited a greater number of cycles that had no clear P-E transition than did UN subjects; this effect disappeared once injections stopped. These alterations suggest immediate, and possibly persisting, alterations in the control of ovulation after chronic cocaine exposure throughout adolescence. Interestingly, during the injection period, the saline-injected females had a significantly greater number of diestrus days compared to uninjected and cocaine-injected animals, as well as a lower proportion of regular 4- and 5-day cycles. These differences disappeared once injections stopped. These results suggest a stress-induced irregularity of the estrous cycle, possibly attenuated by cocaine and recoverable after exposure. The present findings indicate that the HPG axis is susceptible to short-term, and possibly to long-term, alterations induced by cocaine exposure throughout the adolescent period.

Cocaine affects progesterone plasma levels in female rats

Female Fischer rats injected with cocaine in a "binge" pattern (15 mg/kg, IP, three times a day, at 1-h intervals) for 1 day had significantly higher levels of progesterone than saline-treated controls (p < 0.001). When analyzed by the stage of the estrous cycle, animals in proestrus showed significantly higher cocaine-induced progesterone plasma levels than those in other stages of the cycle (p < 0.01). Progesterone plasma levels were also increased after a single dose of cocaine (15 mg/kg). However, 3 h postinjection progesterone plasma levels had returned to normal. Thus, cocaine modulation of progesterone plasma levels appears to be an acute effect. In ovariectomized rats pretreated with estrogen, progesterone, or estrogen + progesterone, no significant differences were observed in progesterone plasma levels after acute "binge" pattern cocaine administration. Thus, acute cocaine induced increases in progesterone plasma levels in intact female rats are probably due to an increase in secretion rates of progesterone rather than an acceleration of its biotransformation. Due to the profound effects of progesterone in the modulation of CNS plasticity, the modulation of progesterone plasma level by cocaine may have implications for reproductive processes and neuronal functions of women. Moreover, cocaine may affect the progesterone levels in women utilizing progesterone-based contraception or steroid replacement treatment after menopause.

Prenatal cocaine exposure alters behavioral and neurochemical sensitization to amphetamine in adult rats

This study examined the neurochemical correlates of amphetamine (AMPH)-induced behavioral effects in prenatally saline (PSAL)-exposed or cocaine (PCOC)-exposed male rats. Pregnant Long-Evans rats received saline or saline containing cocaine hydrochloride (20 mg/kg s.c., b.i.d.) from gestational days 15-21. Animals were left with their biological mothers. Adult offspring were exposed to daily saline or AMPH (0.5, 1.5, or 5 mg/kg, i.p.) injections for 7 days. Behaviors were recorded in an open field during the first hour post-injection. PCOC rats did not exhibit behavioral anomalies during habituation to injection-stress or placement in the open field. PCOC rats displayed significant alterations in stereotyped responses to acute or intermittent exposure to various doses of AMPH. Within 48 h of the final testing day, striatal tissue was obtained from these animals and electrically-evoked [3H]acetylcholine (ACh) release was measured from striatal slices. Superfusion of tissue slices with various concentrations of AMPH (1-1000 nM) produced dose-dependent inhibition of ACh release in both PSAL and PCOC rats repeatedly injected with saline as adults. However, AMPH-induced inhibition of ACh release was decreased in PCOC rats repeatedly injected with AMPH as adults. At 5 mg/kg AMPH, PCOC rats exhibited increased mortality compared to PSAL rats. These data suggest that PCOC exposure produces long-lasting alterations in nigrostriatal transmission and behaviors mediated by this system.

A dose-response study of chronic cocaine on maternal behavior in rats

To determine if there was a dose-response relationship with regard to cocaine treatment and maternal behavior exhibited by lactating rats at doses that had not been previously investigated, we examined the effects of three doses of chronic cocaine administration throughout gestation on both onset and established maternal behavior. Dams were injected (SC) with 6.3, 13, or 25 mg/kg cocaine HCl or an equivalent volume of saline throughout gestation; maternal behavior was tested on postpartum days 1 and 3. At the doses employed, cocaine disrupted the onset of only one pup-directed component of maternal behavior significantly in a dose-response manner, although there were several statistically nonsignificant dose-dependent trends of behavioral disruptions. No pup-directed behaviors were disrupted during testing for established maternal behavior. These results indicate that gestational cocaine treatment at doses of 25 mg/kg and less have only minimal effects on the onset and no effect on the maintenance of maternal behavior using our paradigm. The relationship of the present findings to previous work is discussed.

Cognitive functioning in 8- to 18-month-old drug-exposed infants

This study examined the cognitive functioning in 236 infants at 8 and 18 months of age. Thirty-seven infants were heavily exposed to cocaine in-utero, 30 were lightly exposed, and 169 were not exposed to cocaine. Cognitive functioning was evaluated with the Bayley Scales of Infant Development (2nd ed.; N. Bayley, 1993) at both ages. Infant information processing was also assessed with an infant-controlled habituation procedure. Results indicated that (a) infants of cocaine-abusing women had higher neonatal medical and environmental risk scores; (b) at 8 months, exposure groups did not differ in Psychomotor Development Index, Mental Development Index (MDI) scores, or recovery to a novel stimulus; and (c) infants heavily exposed to cocaine or high environmental risk had a decrease in MDI scores from 8 to 18 months. These results were obtained when neonatal medical and environmental risk, as well as polydrug exposure, were controlled.

Transplacental cocaine exposure. 2: Effects of cocaine dose and gestational timing

We have utilized a mouse model of transplacental cocaine exposure to investigate the effects of cocaine dose and gestational timing in altering brain and body growth and postnatal behavior in exposed offspring. Pregnant dams were injected with cocaine HCl at 40 mg/kg/day (COC 40) or 20 mg/kg/day (COC 20), or 10 mg/kg/day (COC 10) SC from embryonic day (E) 8 to E17, or cocaine HCl at 40 mg/kg/day SC from E8 to E13 (COC Early) or from E13 to E17 (COC Late) divided in two daily doses. COC 40 and COC Late dams, as well as dams in nutritionally paired control groups (injected with saline vehicle and pair-fed with the COC dams: SPF 40, SPF 20, SPF 10), demonstrated less weight gain than SAL controls (injected with saline vehicle and allowed access to food ad lib). The surrogate fostered offspring of COC 40 and SPF 40 dams demonstrated brain and body growth retardation [on postnatal day (P) 1 and P9] when compared to pups born to SAL dams. Offspring of COC Late, SPF 20, and SPF 10 dams demonstrated brain and body growth retardation on P1 when compared to pups born to SAL dams. Pups from all groups were tested for first-order Pavlovian conditioning on P9, or for the ability to ignore redundant information in a blocking paradigm on P50. Only COC 40 mice (i.e., offspring born to COC 40 dams) were unable to acquire an aversion to an odor previously paired with shock on P9. When compared with SAL controls, COC 40 mice (and to a less significant extent SPF 40 mice) demonstrated a persistent behavioral deficit in the blocking paradigm on P50, which may reflect alterations in selective attention. Correlation analyses indicated that the dose and gestational timing of transplacental cocaine exposure, and varying degrees of malnutrition, had effects on blocking performance, with greater prenatal cocaine exposure and increased prenatal malnutrition resulting in more significant behavioral impairments. A path regression analysis demonstrated independent and significant effects of prenatal cocaine as well as prenatal malnutrition in contributing to impaired performance in the blocking paradigm. As suggested by the clinical literature, our preclinical data support a model whereby the dose and duration of prenatal cocaine exposure have direct effects on offspring brain and body growth and on behavioral performance.

Maternal cocaine exposure alters mesolimbic dopaminergic function in rat offspring

Hooded Lister female rats were treated with either saline or cocaine (20 mg/kg s.c.) from gestational day 10 every other day until weaning (postnatal day 25). In vivo microdialysis has shown that maternal cocaine exposure significantly decreases basal extracellular concentrations of dopamine in the nucleus accumbens of young-adult offspring (4 weeks after cessation of cocaine treatment). Moreover, the increase in extracellular dopamine levels induced by a challenge dose of K+ (intracerebral 60 mM K+ artificial cerebrospinal fluid (aCSF) infusion) or cocaine (15 mg/kg i.p.) was significantly attenuated in rats exposed to cocaine during perinatal life with respect to controls. The alterations in mesolimbic dopamine transmission observed in these experiments might underlie behavioral abnormalities induced in rat offspring by maternal exposure to cocaine at dose levels which do not produce gross malformations and/or overt neurotoxic effects.

The thymolytic effect of cocaine and monoaminergic drugs in the mouse

Cocaine abuse is known to be associated with suppression of the immune system. In this experiment, animals treated with cocaine (CC) in their drinking water (200 mg/L) for 10 days resulted in a significant decrease in thymus weight in HSD-NDA male Swiss mice. A subsequent in-vitro experiment was designed to investigate the direct effect of cocaine and other dopaminergic agents on thymocyte proliferation. Thymus glands were aseptically removed from mice and thymocytes were isolated and then incubated in microtiter plates with various concentrations (10[-8]-10[-4] M) of CC, apomorphine (AM), haloperidol (HP), dopamine (DA) and epinephrine (EN) for 18 hrs. The results revealed that cocaine inhibits [3H]-thymidine uptake into DNA in a dose-dependent manner. Apomorphine, haloperidol and dopamine also exhibited a similar dose dependent inhibition of thymocyte proliferation. The IC25s for DNA synthesis inhibition were 8.2 x 10(-6) M, 4.3 x 10(-7) M, 2.5 x 10(-7) M, and 1.1 x 10(-7) M for CC, HP, DA and AM, respectively. EN was found not to have any significant effect on DNA synthesis. The results suggest that thymus gland atrophy, associated with use of CC may be related to the inhibition of thymocyte proliferation.

Prenatal cocaine exposure produces gender-specific motor effects in aged rats

This investigation employed a longitudinal analysis of a complex motor skill in rats that were exposed prenatally to cocaine. Offspring were derived from four maternal treatment groups: 50 mg/kg cocaine, their pair-fed controls, 25 mg/kg cocaine, and freely fed controls. Cocaine was administered via gavage from gestation day 6-20. A maternal fostering procedure was used. Pairs of male and female littermates began training when 9, 13, or 19 months old. The behavioral procedure involved fixed-ratio (FR) lever pressing to obtain brief periods of wheel running. The oldest males from the 50 mg/kg, 25 mg/kg, and pair-fed groups performed significantly fewer wheel revolutions per opportunity than females or freely fed males. In general, animals earned fewer opportunities to run as the FR requirement was increased over sessions. However, within each age-by-gender group, subjects from the four treatment groups performed equivalent amounts of lever pressing. The specific effect on the motor aspect of the procedure may have resulted from a reduction of motor coordination, balance, or strength, or a diminished capacity of wheel running to serve as a reinforcing stimulus in a cocaine-sensitive subgroup.

Dose-dependent effects of multiple acute cocaine injections on maternal behavior and aggression in Sprague-Dawley rats

Rat dams, which had no prior drug treatment, were either nontreated controls or were injected subcutaneously 4 times during a 10-day period with a single dose of 30, 15 or 7.5 mg/kg of cocaine hydrochloride HCl, or normal saline. Injections were given immediately postpartum following delivery of their final pup (PPD 1), and again on postpartum day 3 (PPD 3), postpartum day 6 (PPD 6) and postpartum day 10 (PPD 10). Dams were observed 30 min following injections for maternal behavior (MB) towards 8 surrogate male pups on PPD 1 and PPD 3 and for aggression towards a male or female intruder in the presence of their litter on PPD 6 and PPD 10. Compared to saline and untreated controls, cocaine-treated dams exhibited more disruptions in MB on both PPD 1 and PPD 3 and were less aggressive towards an intruder, regardless of intruder sex, on PPD 6 and PPD 10. In most cases MB was altered in a dose-dependent manner with the higher doses of cocaine resulting in a greater disruption of behavior.

A case report on drug screening of nail clippings to detect prenatal drug exposure

In a case of a sudden infant death syndrome-related death of a 3-month-old infant, nail clippings were positive for cocaine by gas chromatography-mass spectroscopy analysis that revealed a prenatal exposure to the drug substance. In utero exposure to drugs has been investigated using amniotic fluid, neonatal urine, meconium, and hair samples. Nail analysis offers some advantage over hair analysis because of its continuous growth and persistence after delivery. Nail material is easy to sample in suitable amounts. Currently, the cocaine finding cannot be related to the underlying cause of death. However, this observation indicates that nail analysis may be a new and valuable tool to screen newborns for intrauterine drug exposure. In addition, it can help collect information on the prevalence of possible embryotoxic effects and the link to postnatal manifestations of different dysfunctions in infants who are born by drug abusing mothers.

Elevated plasma norepinephrine after in utero exposure to cocaine and marijuana

OBJECTIVE

To compare plasma catecholamine concentrations between cocaine-exposed and unexposed term newborns and to determine the relationship between plasma catecholamines and newborn behavior.

METHODS

Forty-six newborn infants participating in a prospective study of the neonatal and long-term effects of prenatal cocaine exposure were studied. Based on maternal self-report, maternal urine screening, and infant meconium analysis, 24 infants were classified as cocaine-exposed and 22 as unexposed. Between 24 and 72 hours postpartum, plasma samples for norepinephrine (NE), epinephrine, dopamine, and dihydroxyphenylalanine analysis were obtained. The Neonatal Behavioral Assessment Scale was administered at 1 to 3 days of age and at 2 weeks of age by examiners masked to the drug exposure status of the newborns.

RESULTS

The cocaine-exposed newborns had increased plasma NE concentrations when compared to the unexposed infants (geometric mean, 923 pg/mL vs 667 pg/mL). There were no significant differences in plasma epinephrine, dopamine, or dihydroxyphenylalanine concentrations. Analysis for the effect of potential confounding variables revealed that maternal marijuana use was also associated with increased plasma NE, although birth weight, gender, and maternal use of alcohol or cigarettes were not. Geometric mean plasma NE was 1164 pg/mL in those infants with in utero exposure to both cocaine and marijuana compared to 812 pg/mL in those exposed to only cocaine and 667 pg/mL in those exposed to neither. Among the cocaine-exposed infants, plasma NE concentration correlated with an increased score for the depressed cluster (r = .53) and a decreased score for the orientation cluster (r = -.43) of the Neonatal Behavioral Assessment Scale administered at 1 to 3 days of age. Adjusting for marijuana exposure had no effect on these relationships between plasma NE and the depressed and orientation clusters.

CONCLUSION

Plasma NE is increased in newborns exposed to cocaine and marijuana. Increased plasma NE is associated with selected neurobehavioral disturbances among cocaine exposed infants at 1 to 3 days of life but not at 2 weeks.

Neonatal cocaine alters behavioural responsiveness to scopolamine and cholinergic development in mice

CD-1 mice received daily subcutaneous injections of either cocaine (20 mg/kg or 40 mg/kg) or saline solution (0.9% NaCl) from postnatal days 2 to 15. Pups were tested on days 16-17 for learning and 24-h retention of a passive avoidance task, where entering a dark compartment was punished with a mild foot shock. Locomotor activity and general behaviour in an open field arena were assessed on day 21, following administration of either the muscarinic blocker scopolamine (0.8 mg/kg) or saline solution. In addition, immunostaining for the enzyme choline acetyltransferase (ChAT) was measured in different basal forebrain areas (medial septum, striatum, and nucleus basalis) on day 30. Cocaine treatment failed to affect either learning or retention capabilities. Nonetheless, neophobic behaviour during the learning session was enhanced in control nonpunished mice exposed to the 20-mg/kg dose. In the open field test, although baseline activity levels were unaffected by cocaine exposure, the 40-mg/kg cocaine-treated pups showed decreased sensitivity to the hyperkinetic effects of scopolamine. ChAT immunocytochemistry revealed a significant reduction of the number of ChAT-immunopositive neurons in the nucleus basalis but not in the other cholinergic basal forebrain regions.

Immunologic effects of cocaine in prenatally exposed rats and mice

The immunotoxicity of prenatal cocaine exposure was investigated using Sprague-Dawley rats and C57B1/6 mice. Pregnant animals were injected twice a day with cocaine or saline from gestation day 5 until the day before parturition. The immune system of the rat offspring was evaluated at 8 weeks of age by measuring the antibody response to SRBC (plaque assay and serum IgM), delayed-type hypersensitivity response to KLH, and lymphocyte subpopulations in the spleen and thymus using flow cytometry. The immune system of the mice offspring was evaluated at 4 weeks of age by measuring spleen cell proliferation in response to KLH, LPS, and alphaCD3 and IgG production to KLH. From the differences observed between cocaine exposed animals and controls, we conclude that prenatal cocaine exposure does not cause lasting detrimental effects on the immune system, but instead, may enhance B-cell responsiveness.

Effect of sub-chronic cocaine and lidocaine exposure on the lymphoid tissues in neonatal rats

Illicit cocaine varies in purity and is often adulterated with local anesthetics such as lidocaine. Chronic cocaine exposure is associated with immunological modulation in humans and animal models. The effect of sub-chronic oral exposure to cocaine (COC) and lidocaine (LIDO) alone and in combination on the lymphoid organs was assessed in neonatal rats. Lewis rat pups were orally administered saline (SAL), COC, LIDO or both drugs in combination, 20 mg/kg each, from birth to day 21. Statistically significant (P < 0.05) decreases in lymphocyte and total leukocyte levels as well as decreases in spleen weight were observed in pups treated with COC alone. LIDO alone did not affect these parameters in comparison to SAL treated controls. Rats receiving COC and LIDO did not display a significant reduction in spleen weight or in the blood cell populations studied. However, rats treated with COC and LIDO in combination had significantly decreased serum immunoglobulin M (IgM) concentration. Quantitative plasma and tissue analyses ascertained the concentrations and tissue disposition of each drug following oral administration. The results suggest that the effect of COC on the lymphoid tissues and white blood cell parameters is modified in the presence of LIDO in the developing rat.

Effects of prenatal cocaine exposure on the mesocorticolimbic dopamine system: an in vivo microdialysis study in the rat

Microdialysis studies were conducted on prenatally saline-treated and prenatally cocaine-treated rats, either as pups (10-30 days old) or young adults (40-190 days old), to study the effects of prenatal cocaine exposure on the mesolimbic dopamine (DA) system. In the n. accumbens of saline-treated rats, basal dialysate concentrations of DA were similar in pups and adults; however, the levels of DA metabolites, DOPAC, HVA, and the serotonin metabolite, 5-HIAA, were markedly lower in pups. In pups, prenatal cocaine exposure led to basal dialysate levels of DA in the n. accumbens that were twice control levels; however, there was no difference in response to a period of intermittent tail pinch or an acute injection of cocaine (20 mg/kg). In the adult, basal levels of DA, DOPAC, HVA and 5-HIAA in n. accumbens did not differ across prenatal treatments. However, in prenatally cocaine-treated adults a cocaine injection led to an enhanced rise in extracellular DA compared to controls. In frontal cortex of adult rats, basal levels of DA, DOPAC and HVA did not differ across prenatal treatments; however, basal levels of 5-HIAA in this region were significantly elevated in prenatal-cocaine rats. No group differences were observed in the frontal cortex in response to either tail pinch or cocaine. Thus prenatal cocaine exposure produces an increase in basal extracellular DA in the n. accumbens of pups which returns to normal with aging. While this initial difference normalizes, prenatal cocaine exposure induces other persistent changes in adulthood.

Differential effects of prenatal cocaine and retinoic acid on activity level throughout day and night

Prenatal cocaine exposure is associated with disrupted state control and lowered activity levels. Prenatal retinoic acid excess also influences activity levels in laboratory rats. Activity level is usually monitored during a brief period in young offspring. The effects of these drugs on pup activity levels throughout the day is unknown. There is also little information on the long-lasting effects of these teratogens in adult animals. We compared the daily activity of rats which were prenatally exposed to cocaine or retinoic acid (RA). Appropriate control groups were also used. The offspring were evaluated for activity levels in a neophobic situation and for a 22-h period in same-sex groups of 3 littermates. As both pups and adults, the cocaine groups were hypoactive while the RA group was hyperactive when first placed into the testing cage (neophobic situation). Similarly, during the remainder of the 22-h testing period, the pup and adult cocaine animals exhibited reduced activity levels while the RA animals exhibited elevated activity levels. Thus, prenatal cocaine and retinoic acid exposures affected offspring activity levels differently, both drugs have long-lasting neurobehavioral effects that persist into adulthood, and effects are influenced by time-of-day. Strain-dependent differences and mechanisms of action are discussed.