Cocaine, pregnancy, and the growing child

Biparental care in C57BL/6J mice: effects on adolescent behavior and alcohol consumption

RATIONALE

Social attachment plays an important role in offspring development. Different parenting experiences during lactation may shape offspring behavior and later alcohol use.

OBJECTIVES

We tested the hypothesis that differential rearing conditions (single mother, SM or biparental, BP) in the non-monogamous C57BL/6J mice may affect (1) parental behavior during lactation, (2) adolescent behavior, and (3) adolescent initiation of alcohol drinking.

METHODS

Mice were reared in SM or BP (cohabitation of father-mother since copulation) condition until weaning (postnatal day, PND, 21). Litters from both conditions were filmed during PNDs 6, 9, and 12 and an ethogram was made taking into account nest-, pup-, or self-directed behaviors. At PNDs, 28-29 adolescent animals were evaluated in a modified version of the concentric square field for measurement of behavioral patterns. Other groups of adolescents were tested in a 4-h daily, two-bottle choice alcohol consumption test (10% alcohol vs. water) during 3 weeks (4 days per week).

RESULTS

Single mothers spent less time in the nest, left unattended the nest more times, displayed more self-directed and less pup-directed behaviors than BP parents. SM-reared adolescents displayed more anxiogenic-like and less risk-associated behaviors than BP counterparts. The alcohol consumption test indicated a strong effect of rearing condition. Since the fifth day of test, SM adolescents consumed more quantities of alcohol than BP adolescents.

CONCLUSIONS

During single-mother parenting, pups are left unattended more often, and during adolescence, these organisms exhibited increased anxiety responses. This behavioral phenotype may act as a risk factor for alcohol initiation during adolescence.

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.

Neonatal amphetamine exposure and hippocampus-mediated behaviors

Previous studies linking amphetamine use during pregnancy to changes in the behavioral development of affected infants have greatly increased society's level of concern regarding amphetamine use by women of reproductive age. The aim of this study was to investigate whether exposure to d-amphetamine sulfate during the brain growth spurt, the most dynamic period of brain development, alters hippocampus-mediated behaviors during both pre-adolescence and young adulthood. Sprague-Dawley rat pups were intragastrically administered a milk formula containing 0, 5, 15 or 25 mg/kg/day of amphetamine from postnatal day (PD) 4-9. Following weaning, the effects of neonatal amphetamine exposure on hippocampus-mediated behaviors were assessed using the open-field, the water maze, and the conditioned taste aversion behavioral tasks. Results from these behavioral tests revealed that while amphetamine exposure during the brain growth spurt alters behaviors in open-field testing, it does not interfere with performance in either the water maze or the conditioned taste aversion paradigm. These results offer speculation that the effects of neonatal amphetamine exposure on hippocampus-mediated behaviors may be related to interactions between the "temporal" (time of drug exposure) and "regional" (different regions of the hippocampus) vulnerability issues.

Upregulation of Bax and Bcl-2 following prenatal cocaine exposure induces apoptosis in fetal rat brain

Cocaine abuse during pregnancy has been associated with numerous adverse perinatal outcomes.

AIMS

The present study was to determine whether prenatal cocaine exposure induced apoptosis and the possible role of Bcl-2 family genes in the programming cell death in fetal rat brain.

MAIN METHODS

Pregnant rats were treated with cocaine subcutaneously (30 & 60 mg/kg/day) from day 15 to 21 of gestation. Then the fetal and maternal brains were isolated.

KEY FINDINGS

Cocaine produced a dose-dependent decrease in fetal brain weight and brain/body weight ratio (P<0.05). Apoptotic nuclei in fetal brain were increased from 2.6 +/- 0.1 (control) to 8.1+/- 0.6 (low dose) and 10.4 +/- 0.2% (high dose) (P<0.05). In accordance, cocaine dose dependently increased activities of caspase-3, caspase-8, and caspase-9 (% of control) in the fetal brain by 177%, 155%, 174%, respectively, at 30 mg/kg/day, and by 191%, 176%, 274%, respectively, at 60 mg/kg/day. In contrast, cocaine showed no effect on caspase activities in the maternal brain. Cocaine produced a dose-dependent increase in both Bcl-2 and Bax protein expression in the fetal brain, and increased the ratio of Bax/Bcl-2 at dose of 30 mg/kg/day (P<0.05).

SIGNIFICANCE

Our study has demonstrated that prenatal cocaine exposure induces apoptosis in the fetal brain, and suggested that up-regulating Bax/Bcl-2 gene expression may be involved in cocaine-induced apoptosis. The increased apoptosis of neuronal cells in the fetal brain is likely to play a key role in cocaine-induced neuronal defects during fetal development.

Neonatal illicit drug screening practices in Iowa: the impact of utilization of a structured screening protocol

OBJECTIVE

The purpose of the study was to determine the neonatal illicit drug screening practices of Iowa birthing hospitals.

STUDY DESIGN

Cross-sectional survey design was implemented. The impact of structured screening protocols on the numbers of neonates screened and positive testing in 2004 was reviewed.

RESULTS

Of 81 birthing hospitals, 53 (65%) participated in the study. Screening and positive test rates were higher in hospitals utilizing a structured screening protocol compared to those not utilizing one (10.9 versus 2.1% and 0.9 versus 0.2%, respectively, P < 0.0001). Hospitals with higher population, numbers of outpatients, inpatients, deliveries, and availability of drug abuse treatment services utilized a structured screening protocol more often.

CONCLUSION

Utilization of a structured screening protocol increases the number of neonates screened for illicit drugs and positive testing rate regardless of urbanization. Regional standardization of structured screening protocols may improve the recognition of perinatal illicit drug exposure and provision of treatment services.

Physician attitudes concerning legal coercion of pregnant alcohol and drug abusers

OBJECTIVE

We sought to determine the attitudes of obstetricians, pediatricians, and family practice physicians in Michigan concerning involvement of the criminal justice system in preventing drug and alcohol abuse during pregnancy.

STUDY DESIGN

Physicians were sent a questionnaire by mail asking for their agreement with statements concerning the involvement of the criminal justice system with respect to substance abuse during pregnancy.

RESULTS

Nearly all (95%) agreed that pregnant women have a moral duty to ensure they had healthy babies; 59% agreed that they should also have a legal responsibility to do so. Most physicians (77%) agreed that screening for acquired immunodeficiency syndrome during pregnancy should be mandatory. Almost as high a percentage (61% to 75% depending on subspecialty) were also in favor of mandatory screening for alcohol abuse; agreement for screening for illicit drugs was much lower (43% to 55% depending on subspecialty). Despite their consensus (61%) that fear of prosecution would deter pregnant abusers from seeking prenatal care, most were in agreement that existing laws regarding child abuse and neglect need to be redefined to include alcohol (54%) and drug abuse (61%) during pregnancy; 52% were in favor of enacting a statute that includes drug or alcohol use during pregnancy as "child abuse" for purposes of removing that child from maternal custody. Physicians were highly in favor of compulsory treatment for illicit drug use and alcohol abuse for women already in the criminal justice system (82%-83%), neutral with respect to court-ordered contraception for alcohol- (50%) and drug-abusing women (47%), and opposed to criminal prosecution for either alcohol abuse (18%-31% depending on subspecialty) or illicit drug use (23%-34%) during pregnancy.

CONCLUSIONS

Other than criminal prosecution, physicians are not opposed to involvement of the legal justice system in preventing alcohol and drug abuse during pregnancy.

Prenatal cocaine exposure

Cocaine abuse is a significant problem not only in the general population but also among pregnant women. Since cocaine readily crosses the placenta and is metabolized slowly in fetuses, they can be exposed to significant levels of cocaine for long periods. In humans the most common consequences of cocaine abuse during pregnancy include premature birth, lower birth weight, respiratory distress, bowel infarctions, cerebral infarctions, reduced head circumference, and increased risk of seizures. Behaviorally these newborns show an increased degree of "tremulousness," crying and irritability, and are over-reactive to environmental stimuli. Within a month these behaviors have recovered dramatically, but not to normal levels. Thus while there are a number of abnormalities associated with cocaine-exposed neonates, they are not imminently debilitating or life-threatening. However, the long-term consequences of this prenatal cocaine exposure remain to be elucidated. We have examined a rat model for neurochemical, neuroanatomical and behavioral changes resulting from prenatal cocaine exposure. Since cocaine is known to act by blocking the inactivation of the neurotransmitters dopamine, serotonin and norepinephrine, our studies have focused on brain dopamine (DA) and serotonin (5-HT) pathways. In this model system we have found neurochemical changes that are present at birth and that return to normal as the rat ages--similar to the recovery observed in infants. However, there are other neurochemical, anatomical and behavioral changes that persist after birth which may provide insights into the long-term consequences. It is hoped that by understanding the changes occurring in this rat model we will be better prepared to devise pharmacological interventions to circumvent the secondary consequences of prenatal cocaine exposure. These consequences might include increased susceptibility to drug addiction, seizures, depression, schizophrenia, Parkinson's disease, etc.

Parental stress and child behavioral outcomes following substance abuse residential treatment. Follow-up at 6 and 12 months

Residential treatment programs specifically designed for alcohol/drug-addicted women and their children have become a popular treatment modality across the United States. Outcome evaluation of these programs are beginning to show promising results. In this article, outcome data from a study of a residential substance abuse treatment program for women and young children in rural South Carolina will be presented. Data from 35 women and 23 children in the area of addiction severity, parenting and child emotional and behavioral development at 6 and 12 months following discharge from a substance abuse residential treatment program is examined. Results showed that women who completed treatment had better scores on addiction severity and parental stress, and their children had improved behavioral and emotional functioning at 6 and 12 months after discharge from the program. These results suggest that residential treatment has benefits for mothers and their children. This data adds to the growing body of evidence supporting intensive and inclusive care for certain groups of individuals with substance use disorders during critical periods.

Effects of prenatal cocaine exposure and postnatal environment on child development

Studies on the long-term developmental effects of in utero cocaine exposure are few and the small number of studies published do not consider the postnatal environment. The present investigation was conducted to quantify the role that postnatal environment played compared to prenatal exposure. Four groups of 25 infants, each assessed at 12 months of age, were included in the study design: 1) noncocaine-exposed children residing with their biological parents in low socioeconomic environments, 2) cocaine-exposed children living with their biological parents in low socioeconomic environments, 3) noncocaine-exposed children adopted at birth in middle to upper-middle socioeconomic environments, and 4) cocaine-exposed children adopted at birth. Infants were assessed by the Uzgiris-Hunt Ordinal Scales of Infant Psychological Development, the Fagan Test of Infant Intelligence, and the Infant Monitoring Questionnaire. Height and head circumference were measured. Gender and ethnicity were controlled statistically. Significant differences were found in cognitive functioning, in fine motor development, and in physical growth between control and prenatally cocaine-exposed children. Adoption enhanced cognitive functioning and fine motor skills among infants not exposed to cocaine prenatally, but had no apparent effect on infants prenatally exposed to cocaine. Am. J. Hum. Biol. 12:417-428, 2000. Copyright 2000 Wiley-Liss, Inc.

Effect of cocaine, 95% oxygen and ellagic acid on the development and antioxidant status of cultured rat embryos

Prenatal exposure to cocaine has been associated with adverse developmental effects and current data suggest cocaine induced malformations are caused by ischemic-reperfusion injury. This study was undertaken to assess a new in vitro model which uses a routine rat whole embryo culture system that incorporates a change in oxygen status, and to examine the effects of altered oxygen status and pretreatment with ellagic acid (EA), an anti-oxidant, after cocaine exposure. Embryos were evaluated by determining a developmental score and by measuring tissue reduced glutathione (GSH) levels. Following re-oxygenation with 95% O2 for the last 6 h of culture, embryos treated with cocaine had reduced developmental scores and GSH levels. Embryos treated with cocaine and not re-oxygenated with 95% O2 did not have reduced developmental scores. EA blocked the effects of cocaine on developmental score and GSH level. These data support ischemia-reperfusion injury as the mechanism of cocaine developmental toxicity.

The impact of prenatal drug exposure on the neonate

Several social or recreational drugs singly or together have demonstrated effects on the fetus and neonate, with those effects extending into adulthood. The use of recreational drugs during pregnancy remains a major health problem, with adverse effects including higher rates of fetal distress and demise, lower Apgar scores, growth retardation, and adverse neurodevelopmental outcome. Ethanol has the most profound effects, with physical stigmata of the drug seen in one third of exposed infants. In children without the affected physical appearance, profound neurodevelopmental sequelae have been demonstrated. Other drugs, such as cocaine, heroin, amphetamines, and nicotine, have been associated with impaired fetal growth and acute withdrawal during the neonatal period. Subsequently, these infants and children have an increased risk for altered neurodevelopment and long-term health status. Long-term follow-up and assessment are essential. The risk of neonatal withdrawal or abstinence syndrome is greatest with narcotic drugs but has been found to occur in neonates following exposure to cocaine, nicotine, and amphetamines. Early treatment with tincture of opium, paregoric, or phenobarbital is crucial. Assessment of the overall health status of the infant should include growth parameters, signs and symptoms of infection (especially hepatitis, syphilis, and immunodeficiency viruses), and neurobehavioral function. Such assessments should not be limited to the newborn period, as neurodevelopmental sequelae may not be manifest until later in infancy and childhood. In addition, evaluation of the social milieu is warranted because of the increased risk for neglect and abuse of drug-exposed infants and children. Early intervention, maternal drug rehabilitation treatment, and parenting classes are frequently prescribed, but their efficacy is variable. Further investigations should study the potential benefits of these recommendations.

Substance abuse in pregnancy. A bigger problem than you think

Many people think of crack and heroin addiction when they hear the words "substance abuse," but legal substances, such as alcohol, tobacco, amphetamines, and benzodiazepines, can also be abused. When a pregnant women is the abuser, she is potentially damaging two persons. And, since abusers rarely abuse just one substance, the growing fetus may bear the negative impact of multiple substances. Dr King maintains that many pregnant women would try to reduce their substance use if they understood the potential outcome of their actions, and he calls for physicians to identify and counsel women who need help confronting their problem.

Cost-effectiveness of treatment for drug-abusing pregnant women

Neonatal intensive care unit (NICU) and drug treatment costs were compared in two groups of pregnant drug abusing women: 100 admissions to a multidisciplinary treatment program and active in care at the time of delivery and 46 controls not entering drug treatment. Clinical measures included urine toxicology at delivery, infant birthweight. Apgar scores and need for and duration of NICU services. Cost measures included drug treatment and NICU costs. Treatment patients showed better clinical outcome at delivery, with less drug use and higher infant estimated gestational age, birthweight and Apgar scores. Infants of treatment patients were also less likely to require NICU services and, for those that did, had a shorter stay. When total cost was examined (including drug treatment), mean net savings for treatment subjects was $4644 per mother/infant pair. The study demonstrates the cost-effectiveness of treatment for pregnant drug abusing women, with savings in NICU costs exceeding costs of drug treatment.

A prospective evaluation of early language development in children with in utero cocaine exposure and in control subjects

A cohort of children of low socioeconomic status, 76 with in utero cocaine exposure and 81 control subjects, was assessed for early language development at 2 1/2 years of age by a masked examiner using the Preschool Language Scale. There were no differences between groups in expressive, receptive, or total language score (all p > or = 0.57). Physicians caring for cocaine-exposed children with early language delay should not automatically ascribe the delay to cocaine exposure but should initiate a standard evaluation for language delay.

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.

A murine model of prenatal cocaine exposure: effects on the mother and the fetus

To develop and characterize a murine model for investigating the long-term effects of prenatal cocaine exposure, the present study established the route of drug administration and the doses to be used for pregnant C57BL/6 mice. Comparison of the effects of a high dose of cocaine (60 mg/kg) when gavaged or injected subcutaneously (SC) established patterns of pathology characteristic of administration route but no dominating logic for selecting one over the other route for prenatal studies; however, because of the fourfold greater brain levels, with no evidence of greater pathology, the SC route was selected. When injected daily during gestation days 12-18, the period of prenatal development of dopamine systems, cocaine at doses producing plasma concentrations consistent with its stimulatory effects reduced food ingestion and weight gains during pregnancy and fetal body and brain weights at term. The extent of these reductions was comparable to reports on babies exposed to cocaine prenatally. Furthermore, the present study suggests that maternal undernutrition is not a likely mediator of these perinatal effects and that differences in the amount of cocaine exposure may cause the contrasting effects of maternal cocaine noted in the human literature.

Enhanced cocaine self-administration in adult rats prenatally exposed to cocaine

Rats that had been prenatally exposed to either cocaine or saline were examined as adults using continuous reinforcement (FR1) cocaine self-administration. Initially these rats were water-deprived and trained to bar-press for water; no differences across prenatal treatments were observed during this training phase. After complete rehydration and implantation of an intravenous cannula into the external jugular vein, animals were introduced to cocaine self-administration with a nocturnal and subsequent 3 h exposure. During daily test sessions rats were allowed to self-administer cocaine for 1 h/day. Prenatal cocaine exposure led to a marked and stable enhancement of the rates of self-administration for up to 13 days, the longest time point examined. These results suggest that prenatal cocaine exposure can alter cocaine reinforcement in adult animals.

Physiological and behavioral effects of early embryonic exposure to ethanol and cocaine in the young chick

The physiological and behavioral effects of embryonic exposure to ethanol and cocaine, given during active neurogenesis (embryonic days E3 and E4), were studied in 1- and 2-day-old chicks. Broiler chicks (n = 131) from five embryonic treatment conditions were tested: incubative controls (n = 28), vehicle (saline plus 50 micrograms/ml bacitracin; n = 27), 10 mg ethanol (n = 20), 150 micrograms cocaine (n = 25), or co-drug (10 mg ethanol and 150 micrograms cocaine; n = 31). Compared with controls, embryo mortality for the cocaine alone embryos was significantly increased. No significant embryonic treatment effects among chicks were found for hatching times, body weights at hatch and testing, and temperature regulation when cold stressed. Behaviorally, chicks were first trained to key-peck for heat/light reward (autoshaping). Chicks in all groups increased responding from autoshape session 1 to session 2 (24 trials/session). In an acquisition-extinction session (12 trials/phase), chicks in all groups except those in the co-drug group decreased responding from acquisition to extinction. In a second acquisition-extinction session following a drug challenge of 0.5 mg/kg apomorphine, chicks in all embryonic treatment groups showed enhanced responding. Hence, in those chicks that survived, the selected doses of ethanol and cocaine produced minimal physiological and behavioral effects individually, but when given together did produce a significant deficit in extinction responding.

Cocaine use in pregnancy in Amsterdam

To study the effects of cocaine use in pregnancy in Amsterdam, clinical data on cocaine-using pregnant women (n = 21) and their offspring (n = 23) were obtained retrospectively (1987-1994) at the Academic Medical Center, Amsterdam. Infants exposed to cocaine had a median gestational age of 39 weeks and a median birth weight of 3090 g. There were six preterm infants, two small-for-gestational-age infants and five infants with a small head circumference. Three infants had a congenital malformation. One infant (Potter's syndrome) died shortly before birth. One infant had congenital syphilis, four had intracerebral abnormalities on ultrasound and four had abnormal neurologic symptoms in the neonatal period. One infant died after 21 days of life. At follow-up four infants showed abnormal development. In 12 of the 23 infants (52%), one or more possible effects of cocaine were found.

Evolution of neonatal seizures

The evolution of the diagnosis, etiology, management, and prognosis of neonatal seizures over the past two decades is reviewed. Seizures in the neonate are unique and require special classification. They result from acquired or congenital abnormalities of the central nervous system. Clustering of prognostic parameters, including seizure characteristics, perinatal factors, neurologic signs, cause, and neuroimaging and electroencephalographic abnormalities, allows neonatal seizures to be viewed as clinical syndromes with predictable outcomes.

A program to address the special needs of drug-exposed children

The Ravenswood-Stanford Coalition for At-Risk Children promotes school success by intervening with K-3 students identified as drug-exposed, either prenatally or environmentally, enabling them to remain in regular classrooms rather than diverted to special education. This goal was accomplished through professional partnerships, home involvement, individual intervention plans, special school-based services, and mentorships. Results from the project indicate these children are not significantly different from their peers; home involvement promotes better school linkages and reinforces positive behavior change; appropriate short-term, school-based services can increase academic and behavioral performance; dedicated volunteers working individually with students accelerate change processes; and these special at-risk students must be assigned to caring, supportive, and predictable classrooms.

Cocaine metabolites in the neonate: potential for toxicity

Recent reports indicate that cocaine metabolites have biologic activity and could be toxic. To explore this possibility, two studies were initiated. The first study aimed to define the distribution of cocaine species by quantifying levels of cocaine and its metabolites norcocaine, benzoylecgonine, and benzoylnorecgonine in newborn cord blood and meconium. The second study sought to determine whether they produced a clinical effect. Compared to cord blood, meconium had a greater number of metabolites and a higher concentration of cocaine metabolites, including the previously undetectable norcocaine and benzoylnorecgonine derivatives. Benzoylecgonine was the most common species found in both sources and was usually lower in concentration in blood. An inverse relation existed between meconium benzoylecgonine levels and the serum catabolic enzyme pseudocholinesterase, implying genetic variability in cocaine metabolism. To determine whether cocaine and/or its metabolites could be linked to a distinct clinical state, a second study focusing on newborn behavior was performed with an independent large cohort of cocaine-exposed infants. Neonates with increased signs of "neuroexcitation" had benzoylecgonine and no cocaine in urine, whereas lethargic neonates had detectable urinary cocaine. These findings support the hypothesis that cocaine metabolites, especially benzoylecgonine, may play a role in altering newborn behavior and produce a clinical syndrome distinct from that related to the parent compound.

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

Pregnant rats were given injections of saline (0.5 ml/kg) or cocaine (10 mg/kg, 20 mg/ml, s.c.) twice daily between gestational days 7-21. Offspring were examined by microdialysis between postnatal days 10-125 to study the effects of prenatal cocaine exposure on the nigrostriatal dopamine (DA) system. Twenty-min dialysis samples were collected and assayed for DA, DOPAC and HVA. After four baseline samples, the rat was exposed to 20 min of intermittent tail pinch and monitored for four samples; then each rat received an acute injection of cocaine (20 mg/kg, i.p.) and six additional samples were collected. Basal dialysate concentrations of all DA markers, estimated from pre-implantation calibration of the probes, were markedly reduced in young rats ('pups', 10-30 days old) as compared with adult rats (40-125 days old). Compared to control pups, basal DA, as well as DOPAC and HVA, were elevated in the prenatal-cocaine pups. Tail pinch (a mild stressor) produced a significant increase in DA only in the pups prenatally exposed to cocaine. The increase in basal DA induced by an acute cocaine injection (20 mg/kg) was also greater and more prolonged in the prenatal-cocaine pups. In older rats (40-125 days) there were no group differences in any of the DA parameters. Thus prenatal exposure to cocaine produces an activation of the DA system which persists after birth but returns to normal in older rats.