Gestational exposure to cocaine alters cocaine reward

Effect of early embryonic exposure to morphine on defects in the GABAergic system of day-old chicks

Embryonic morphine exposure (EME) leads to abnormal brain development and behavior in the offspring, and the functional alteration of γ-aminobutyric acid (GABA) system is considered to be one of the important mechanisms. To mimic the problem of susceptibility of human gestational drug abuse on addictive drugs in offspring, we administered morphine exposure on days 5-8 and 13-16 of chicken embryo development and examined the functions of GABA neurons and their receptors in postnatal chicks by neuroelectrophysiology, immunohistochemistry and behavioral methods. We found that morphine exposure during embryonic stages 5-8 (MorphineE5-8) significantly reduced the incidence of spontaneous inhibitory postsynaptic potentiation (IPSP) and the induction of evoked IPSP and the mean amplitude of GABA_A agonist muscimol-induced response in the intermediate medial interstitial (IMM) region, compared to naïve controls or saline-exposed chicks. The results of immunocytochemistry further suggest that MorphineE5-8 decreased the synaptic density of GAD-expressing sites in the IMM, while increased the expression of the GABA_A receptor subtype γ2 isoform. Behavioral results found that Morphine5-8 treatment de-inhibited morphine-induced psychomotor responses in postnatal chicks. Morphine exposure at embryonic stages 13-16 (MorphineE13-16) showed no significant changes in the above indicators compared to the saline group. Evidence suggests that early embryonic morphine exposure leads to defects in GABAergic function in the IMM, which in turn alters the responsiveness of postnatal chicks to addictive drugs. These results will help to understand the GABA mechanisms by which embryonic addictive drug exposure contributes to offspring susceptibility to addiction.

Prenatal and Postnatal Cocaine Enhances the Induction and Expression of Locomotor Sensitization to Nicotine in Male Rats

INTRODUCTION

Several studies mention that early consumption of cannabis, alcohol, or even cocaine is related to an increase in the prevalence of daily consumption of tobacco in adulthood. However, other factors, such as genetic comorbidity, social influences, and even molecular, neurochemical, and behavioral alterations induced by prenatal and postnatal cocaine exposure, could also explain these observations, since these factors together increase the vulnerability of the offspring to the reinforcing effects of nicotine. The objective of this study was to determine the effect of prenatal and postnatal exposure to cocaine on nicotine-induced locomotor sensitization in young and adult rats.

AIMS AND METHODS

The study was divided into two stages: prenatal and postnatal. In the prenatal stage, a group of pregnant female Wistar rats was administered cocaine daily from day GD0 to GD21 (cocaine preexposure group), and another group of pregnant female rats was administered saline daily (saline preexposure group). Of the litters resulting from the cocaine preexposed and saline preexposed pregnant female groups, in the postnatal stage, only the male rats were used for the recording of the locomotor activity induced by different doses of nicotine (0.2, 0.4, and 0.6 mg/kg) during the induction and expression of locomotor sensitization at different postnatal ages (30, 60, 90, and 120 days).

RESULTS

Prenatal and postnatal cocaine exposure enhanced nicotine-induced locomotor activity and locomotor sensitization.

CONCLUSIONS

This suggests that prenatal and postnatal cocaine exposure can result in increased vulnerability to other drugs of abuse, such as nicotine, in humans.

IMPLICATIONS

Several studies have shown that the abuse of a drug, such as cannabis, alcohol, or even cocaine, at an early age can progress to more severe levels of use of other drugs, such as nicotine, to adulthood. Our data are consistent with this hypothesis, since prenatal and postnatal cocaine exposure enhanced the nicotine-induced increase in locomotor activity and locomotor sensitization. This suggests that prenatal and postnatal exposure to cocaine enhances the drug's salience.

Review of long-term consequences of maternal methamphetamine exposure

Methamphetamine is one of the most abused hard drugs in the Czech Republic. Its popularity is high not only in Eastern Bloc of Europe but is growing in other countries around the world, including the United States. In addition, methamphetamine abuse increases in drug addicts during pregnancy. Although research into the long-term effects of prenatal methamphetamine exposure has been ongoing for many years, the exact mechanism of action and factors that may influence the effect of this drug are still not fully understood. There have been many studies that investigated the effects of addictive substances on the behavior and cognitive function of individuals during adolescence. Some studies have shown prenatal or perinatal influences, e.g. drugs, stress, hypoxia, and malnutrition, can affect drug sensitivity or drug-seeking behavior in adulthood. However, when these factors are most impactful, i.e. prenatal vs. perinatal, and which stages of the prenatal and perinatal periods are the most sensitive to these factors is not yet clear. Our laboratory specializes in research on the effects of drugs (especially methamphetamine) on rat mothers and their offspring during postnatal development, adolescence, and adulthood. This review summarizes our past results on the long-term effects of methamphetamine on the mother and her offspring, its mechanism of action, the role of maternal care, the possible emergence of long-term sensitization, and the critical neurodevelopmental periods for methamphetamine exposure.

Prenatal and postnatal cocaine exposure enhances the induction and expression of locomotor sensitization to cocaine in rats

Prenatal and postnatal exposure to cocaine can affect the development and function of the central nervous system in offspring. It also produces changes in cocaine-induced dopamine release and increases cocaine self-administration and cocaine-induced conditioned place preference. Further, prenatal cocaine exposure involves greater risk for development of a substance use disorder in adolescents. Therefore, the objective of this study was to determine the effect of prenatal and postnatal cocaine exposure on locomotor sensitization in rats. A group of pregnant female Wistar rats were administered daily from day GD0 to GD21 with cocaine (cocaine pre-exposure group) and another group pregnant female rats were administered daily with saline (saline pre-exposure group). During lactation (PND0 to PND21) pregnant rats also received cocaine administration or saline, respectively. Of the litters resulting of the cocaine pre-exposed and saline pre-exposed pregnant female groups, only the male rats were used for the recording of the locomotor activity induced by different doses of cocaine (1, 5, 10, 20 and 40 mg/Kg/day) during the induction and expression of locomotor sensitization at different postnatal ages (30, 60, 90 and 120 days), representative of adolescence and adult ages. The study found that prenatal and postnatal cocaine exposure enhanced locomotor activity and locomotor sensitization, and such increase was dose- and age-dependent. This suggests that prenatal and postnatal cocaine exposure can result in increased vulnerability to cocaine abuse in young and adult humans.

Does Prenatal Methamphetamine Exposure Induce Sensitization to Drugs in Adulthood?

Behavioral sensitization is defined as augmented psychomotor activity, which can be observed after drug re-administration following withdrawal of repeated drug exposure. It has been shown that abuse of one drug can lead to increased sensitivity to certain other drugs. This effect of developed general drug sensitivity is called cross-sensitization and has been reported between drugs with similar as well as different mechanisms of action. There is growing evidence that exposure to drugs in utero not only causes birth defects and delays in infant development, but also impairs the neural reward pathways, in the brains of developing offspring, in such a way that it can increase the tendency for drug addiction later in life. This review summarizes the results of preclinical studies that focused on testing behavioral cross-sensitization, after prenatal methamphetamine exposure, to drugs administered in adulthood, with both similar and different mechanisms of action. Traditionally, behavioral sensitization has been examined using the Open field or the Laboras Test to record locomotor activity, and the Conditioned Place Preference and Self-administration test to examine drug-seeking behavior. However, it seems that prenatal drug exposure can sensitize animals not only to the locomotor-stimulating and conditioning effects of drugs, but may also be responsible for modified responses to various drug effects.

Sex differences in the strategies of spatial learning in prenatally-exposed rats treated with various drugs in adulthood

In the present study we investigated the sex differences in the effect of adult long-term drug treatment on cognitive functions of Wistar rats, which were prenatally exposed to MA (5mg/kg) or saline. Cognitive functions were tested as an ability of spatial learning in the Morris Water Maze (MWM), which consisted of three types of tests: "Place Navigation Test"; "Probe Test", and "Memory Recall Test". Adult animals were injected daily, after completion of the last trial, either with saline or cocaine (COC; 5mg/kg), MDMA (3,4-methylenedioxy-methamphetamine; 5mg/kg), morphine (MOR; 5mg/kg), or delta-9-tetrahydrocannabinol (THC; 2mg/kg). Results revealed worsened MWM performance in female rats after drug treatment in adulthood. Not only were traditionally investigated parameters affected by drug treatment (latency of platform acquisition, search strategy, distance traveled), but also strategies used by animals (thigmotaxis, scanning). Analyses of search strategies observed in the Place Navigation Test, as well as in the Memory Recall Test, demonstrated variations in the percentage of time spent in thigmotaxis and scanning in females after treatment with COC, MDMA, MOR, and THC. Although we did not see a sensitizing effect of prenatal MA, in some cases the effect of drug treatment in adulthood differed depending on the prenatal drug exposure. The data presented in this study demonstrates that exposure to drugs with various mechanisms of action alters spatial abilities of female rats in the MWM. Alterations in the effect of adult drug treatment with reference to prenatal drug exposure were also found in the present study.

Dopamine D2 receptors mediate the increase in reinstatement of the conditioned rewarding effects of cocaine induced by acute social defeat

Social stress modifies the activity of brain areas involved in the rewarding effects of psychostimulants, inducing neuroadaptations in the dopaminergic mesolimbic system and modifying the sensitivity of dopamine receptors. In the present study we evaluated the effect of the dopamine D₁- and D₂-like receptor antagonists (SCH23390 and raclopride, respectively) on the short-time effects of acute social defeat (ASD). Male OF1 mice were socially defeated before each conditioning session of the conditioned place preference (CPP) induced by 1mg/kg or 25mg/kg of cocaine plus the corresponding dopamine antagonist. A final experiment was designed to evaluate the effect of the dopamine antagonists on the CPP induced by 3mg/kg of cocaine with or without a stress experience. Mice exposed to ASD showed an increase in reinstatement of the conditioned reinforcing effects of cocaine that was blocked by all of the dopamine receptor antagonists. Blockade of dopamine D₂-like receptors with raclopride specifically prevented the effects of stress without affecting the rewarding properties of cocaine. However, SCH23390 inhibited cocaine-induced preference in the control groups and even induced aversion in defeated mice conditioned with the lower dose of cocaine. Moreover, the lowest dose of SCH23390 blocked the rewarding effects of 3mg/kg of cocaine-induced CPP. Our results confirm that the dopamine D₂ receptor is involved in the short-term effects of ASD on the rewarding effects of cocaine. The dopamine D₁ receptor is clearly involved in the rewarding effects of cocaine, but its role in the effects of ASD remains to be demonstrated.

Enhanced sensitivity to drugs of abuse and palatable foods following maternal overnutrition

Epidemiological studies have shown an association between maternal overnutrition and increased risk of the progeny for the development of obesity as well as psychiatric disorders. Animal studies have shown results regarding maternal high-fat diet (HFD) and a greater risk of the offspring to develop obesity. However, it still remains unknown whether maternal HFD can program the central reward system in such a way that it will imprint long-term changes that will predispose the offspring to addictive-like behaviors that may lead to obesity. We exposed female dams to either laboratory chow or HFD for a period of 9 weeks: 3 weeks before conception, during gestation and lactation. Offspring born to either control or HFD-exposed dams were examined in behavioral, neurochemical, neuroanatomical, metabolic and positron emission tomography (PET) scan tests. Our results demonstrate that HFD offspring compared with controls consume more alcohol, exhibit increased sensitivity to amphetamine and show greater conditioned place preference to cocaine. In addition, maternal HFD leads to increased preference to sucrose as well as to HFD while leaving the general feeding behavior intact. The hedonic behavioral alterations are accompanied by reduction of striatal dopamine and by increased dopamine 2 receptors in the same brain region as evaluated by post-mortem neurochemical, immunohistochemical as well as PET analyses. Taken together, our data suggest that maternal overnutrition predisposes the offspring to develop hedonic-like behaviors to both drugs of abuse as well as palatable foods and that these types of behaviors may share common neuronal underlying mechanisms that can lead to obesity.

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.

Does Prenatal Methamphetamine Exposure Induce Cross-sensitization to Cocaine and Morphine in Adult Male Rats?

The aim of the present study was to examine the cross-sensitization induced by prenatal methamphetamine (MA) exposure to challenge dose of cocaine or morphine. Rat mothers received a daily injection of MA (5 mg/kg) or saline throughout the gestation period. Adult male offspring (prenatally MA- or saline-exposed) were divided to groups with challenge doses of saline (1 ml/kg), cocaine (5 mg/kg) or morphine (5 mg/kg). Behavior in unknown environment was examined in Laboras, nociception in Plantar test, and active drug-seeking behavior in conditioned place preference (CPP). Our data demonstrate that cocaine increased the exploratory activity in Laboras test in prenatally saline-exposed, but decreased it in prenatally MA-exposed rats. An analgesic effect of cocaine was demonstrated only by the tail withdrawal and it was independent of the prenatal drug exposure. CPP test showed that prenatal MA exposure induced rather tolerance than sensitization to cocaine. In contrast to cocaine effects, morphine decreased rearing activity in both, prenatally MA-exposed and saline-exposed rats, and locomotion only in prenatally MA-exposed rats in the Laboras. In the Plantar test, the results demonstrated that morphine had an analgesic effect in prenatally saline-exposed rats but this effect was suppressed in prenatally MA-exposed rats. In the CPP test morphine induced drug-seeking behavior, which however was not affected by prenatal drug exposure. Thus, our data demonstrate that there is a cross-effect between prenatal MA exposure and the challenge dose of other drug in adulthood, however drug-seeking behavior is not increased by prenatal MA exposure as we expected.

Effects of prenatal cocaine exposure on early postnatal rodent brain structure and diffusion properties

Prenatal cocaine exposure has been associated with numerous behavioral phenotypes in clinical populations, including impulsivity, reduced attention, alterations in social behaviors, and delayed language and sensory-motor development. Detecting associated changes in brain structure in these populations has proven difficult, and results have been inconclusive and inconsistent. Due to their more controlled designs, animal models may shed light on the neuroanatomical changes caused by prenatal cocaine; however, to maximize clinical relevance, data must be carefully collected using translational methods. The goal of this study was two-fold: (1) to determine if prenatal cocaine alters developmental neuroanatomy using methods that are available to human researchers, specifically structural MRI and diffusion tensor imaging, and (2) to determine the feasibility of rodent in vivo neuroimaging for usage in longitudinal studies of developmental disorders. Cocaine-exposed (prenatal days 1-20, 30mg/kg/day) rat pups were sedated and imaged live using diffusion tensor imaging and postmortem (fixed) using magnetic resonance histology on postnatal day 14. Volume and diffusion properties in whole brain as well as specific regions of interest were then assessed from the resulting images. Whole brain analyses revealed that cocaine-exposed animals showed no change in whole brain volume. Additionally, we found alterations in fractional anisotropy across regions associated with reward processing and emotional regulation, especially in the thalamus and globus pallidus, as well as sex-dependent effects of cocaine in the right cortex. Reductions in fractional anisotropy were paired with reductions only in axial diffusivity, which preliminarily suggests that the changes observed here may be due to axonal damage, as opposed to reductions in myelination of the affected regions/pathways. Our data indicate that prenatal cocaine may target a number of developing brain structures but does not result in overt changes to brain volumes. These results highlight not only the brain alterations that result from prenatal cocaine but also the advancements in live imaging that allow longitudinal study designs in other models.

Effect of Amphetamine on Adult Male and Female Rats Prenatally Exposed to Methamphetamine

The aim of the present study was to examine the cross-sensitization induced by prenatal methamphetamine (MA) exposure to adult amphetamine (AMP) treatment in male and female rats. Rat mothers received a daily injection of MA (5 mg/kg) or saline throughout the gestation period. Adult male and female offspring (prenatally MA- or saline-exposed) were administered with AMP (5 mg/kg) or saline (1 ml/kg) in adulthood. Behaviour in unknown environment was examined in open field test (Laboras), active drug-seeking behaviour in conditioned place preference test (CPP), spatial memory in the Morris water maze (MWM), and levels of corticosterone (CORT) were analyzed by enzyme immunoassay (EIA). Our data demonstrate that in Laboras test, AMP treatment in adulthood increased general locomotion (time and distance travelled) regardless of the prenatal exposure and sex, while AMP increased exploratory activity (rearing) only in prenatally MA-exposed animals. AMP induced sensitization only in male rats, but not in females when tested drug-seeking behaviour in the CPP test. In the spatial memory MWM test, AMP worsened the performance only in females, but not in males. On the other hand, males swam faster after chronic AMP treatment regardless of the prenatal drug exposure. EIA analysis of CORT levels demonstrated higher level in females in all measurement settings. In males, prenatal MA exposure and chronic adult AMP treatment decreased CORT levels. Thus, our data demonstrated that adult AMP treatment affects behaviour of adult rats, their spatial memory and stress response in sex-specific manner. The effect is also influenced by prenatal drug exposure.

Prenatal exposure to methylphenidate affects the dopamine system and the reactivity to natural reward in adulthood in rats

BACKGROUND

Methylphenidate (MPH) is a commonly-used medication for the treatment of children with Attention-Deficit/Hyperactivity Disorders (ADHD). However, its prescription to adults with ADHD and narcolepsy raises the question of how the brain is impacted by MPH exposure during pregnancy. The goal of this study was to elucidate the long-term neurobiological consequences of prenatal exposure to MPH using a rat model.

METHODS

We focused on the effects of such treatment on the adult dopamine (DA) system and on the reactivity of animals to natural rewards.

RESULTS

This study shows that adult male rats prenatally exposed to MPH display elevated expression of presynaptic DA markers in the DA cell bodies and the striatum. Our results also suggest that MPH-treated animals could exhibit increased tonic DA activity in the mesolimbic pathway, altered signal-to-noise ratio after a pharmacological stimulation, and decreased reactivity to the locomotor effects of cocaine. Finally, we demonstrated that MPH rats display a decreased preference and motivation for sucrose.

CONCLUSIONS

This is the first preclinical study reporting long-lasting neurobiological alterations of DA networks as well as alterations in motivational behaviors for natural rewards after a prenatal exposure to MPH. These results raise concerns about the possible neurobiological consequences of MPH treatment during pregnancy.

The effects of prenatal cocaine, post-weaning housing and sex on conditioned place preference in adolescent rats

RATIONALE

Gestational exposure to cocaine now affects several million people including adolescents and young adults. Whether prenatal drug exposures alter an individual's tendency to take and/or abuse drugs is still a matter of debate.

OBJECTIVES

This study sought to answer the question "Does prenatal exposure to cocaine, in a dose-response fashion, alter the rewarding effects of cocaine using a conditioned place preference (CPP) procedure during adolescence in the rat?" Further, we wanted to assess the possible sex differences and the role of being raised in an enriched versus impoverished environment.

METHODS

Virgin female Sprague-Dawley rats were dosed daily with cocaine at 30 mg/kg (C30), 60 mg/kg (C60), or vehicle intragastrically prior to mating and throughout gestation. Pups were culled, fostered and, on postnatal day (PND) 23, placed into isolation cages or enriched cages with three same-sex littermates and stimulus objects. On PND43-47, CPP was determined across a range of cocaine doses.

RESULTS

C30 exposure increased sensitivity to the rewarding effects of cocaine in adolescent males, and being raised in an enriched environment further enhanced this effect. Rats exposed to C60 resembled the controls in cocaine CPP. Overall, females were modestly affected by prenatal cocaine and enrichment.

CONCLUSIONS

These data support the unique sensitivity of males to the effects of gestational cocaine, that moderate prenatal cocaine doses produce greater effects on developing reward circuits than high doses and that housing condition interacts with prenatal treatment and sex such that enrichment increases cocaine CPP mostly in adolescent males prenatally exposed to moderate cocaine doses.

Effects of prenatal cocaine/polydrug exposure on substance use by age 15

OBJECTIVE

Examined effects of prenatal cocaine exposure (PCE) on tobacco, alcohol, marijuana and cocaine use by age 15.

METHODS

Adolescent (n=358; 183 PCE, 175 non-prenatally cocaine exposed; NCE) drug use was assessed using urine, hair, and/or blood spot samples and self-report (Youth Risk Behavior Surveillance System; YRBSS) at ages 12 and 15. Logistic regression assessed effects of PCE on drug use controlling for other drug exposures, environment and blood lead levels (BLL).

RESULTS

Adjusted percentages of drug use (PCE vs. NCE) were: tobacco 35% vs. 26% (p<.04), marijuana 33% vs. 23% (p<.04), alcohol 40% vs. 35% (p<.01), and any drugs 59% vs. 50% (p<.005). PCE adolescents were twice as likely to use tobacco (OR=2.02, 95% CI=1.05-3.90, p<.04), 2.2 times more likely to use alcohol (OR=2.16, 95% CI=1.21-3.87, p<.01) and 1.8 times more likely to use marijuana (OR=1.81, 95% CI=1.02-3.22, p<.04) than NCE adolescents. A race-by-cocaine-exposure interaction (p<.01) indicated PCE non-African American adolescents had greater probability of tobacco use (65%) than NCE non-African American youth (21%). PCE was associated with any drug use (OR=2.16, CI=1.26-3.69, p<.005), while higher BLL predicted alcohol use (p<.001). Violence exposure was a predictor of tobacco (p<.002), marijuana (p<.0007) and any drug (p<.04).

CONCLUSIONS

PCE and exposure to violence increased the likelihood of tobacco, marijuana or any drug use by age 15, while PCE and higher early BLL predicted alcohol use. Prevention efforts should target high risk groups prior to substance use initiation.

Gender differences in the effect of prenatal methamphetamine exposure and challenge dose of other drugs on behavior of adult rats

The aim of the present study was to compare the response to acute application of several drugs in adult male and female rats prenatally exposed to methamphetamine (MA). Spontaneous locomotor activity and exploratory behavior of adult male and female rats prenatally exposed to MA (5 mg/kg) or saline were tested in a Laboras apparatus (Metris B.V., Netherlands) for 1 h. Challenge dose of the examined drug [amphetamine - 5 mg/kg; cocaine - 5 mg/kg; MDMA (3,4-methylenedioxymethamphetamine) - 5 mg/kg; morphine - 5 mg/kg; THC (delta9-tetrahydrocannabinol) - 2 mg/kg] or saline was injected prior to testing. Our data demonstrate that prenatal MA exposure did not affect behavior in male rats with cocaine or morphine treatment, but increased locomotion and exploration in females. Application of amphetamine and MDMA in adulthood increased activity in both sexes, while cocaine and THC only in female rats. Morphine, on the other hand, decreased the activity in the Laboras test in both sexes. As far as sex and estrous cycle is concerned, the present study shows that males were generally less active than females and also females in proestrus-estrus phase of the estrous cycle were more active than females in diestrus. In conclusion, the present study shows that the prenatal MA exposure does not induce general sensitization but affects the sensitivity to drugs dependently to mechanism of drug action and with respect to gonadal hormones.

Do prenatally methamphetamine-exposed adult male rats display general predisposition to drug abuse in the conditioned place preference test?

Drug abuse of pregnant women is a growing problem. The effect of prenatal drug exposure may have devastating effect on development of the offsprings that may be long-term or even permanent. One of the most common drug abused by pregnant women is methamphetamine (MA), which is also the most frequently abused illicit drug in the Czech Republic. Our previous studies demonstrated that prenatal MA exposure alters behavior, cognition, pain and seizures in adult rats in sex-specific manner. Our most recent studies demonstrate that prenatal MA exposure makes adult rats more sensitive to acute injection of the same or related drugs than their controls. The aim of the present study was to examine the effect of prenatal MA exposure on drug-seeking behavior of adult male rats tested in the Conditioned place preference (CPP). Adult male rats were divided to: prenatally MA-exposed (5 mg/kg daily for the entire prenatal period), prenatally saline-exposed (1 ml/kg of physiological saline) and controls (without maternal injections). The following drugs were used in the CPP test in adulthood: MA (5 mg/kg), amphetamine (5 mg/kg), cocaine (5 and 10 mg/kg), morphine (5 mg/kg), MDMA (5 mg/kg) and THC (2 mg/kg). Our data demonstrated that prenatally MA-exposed rats displayed higher amphetamine-seeking behavior than both controls. MA as well as morphine induced drug-seeking behavior of adult male rats, however this effect did not differ based on the prenatal MA exposure. In contrast, prenatal MA exposure induced rather tolerance to cocaine than sensitization after the conditioning in the CPP. MDMA and THC did not induce significant effects. Even though the present data did not fully confirmed our hypotheses, future studies are planned to test the drug-seeking behavior also in self-administration test.

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.

Dopamine Genetics and Function in Food and Substance Abuse

Having entered the genomics era with confidence in the future of medicine, including psychiatry, identifying the role of DNA and polymorphic associations with brain reward circuitry has led to a new understanding of all addictive behaviors. It is noteworthy that this strategy may provide treatment for the millions who are the victims of "Reward Deficiency Syndrome" (RDS) a genetic disorder of brain reward circuitry. This article will focus on drugs and food being mutuality addictive, and the role of dopamine genetics and function in addictions, including the interaction of the dopamine transporter, and sodium food. We will briefly review our concept that concerns the genetic antecedents of multiple-addictions (RDS). Studies have also shown that evaluating a panel of established reward genes and polymorphisms enables the stratification of genetic risk to RDS. The panel is called the "Genetic Addiction Risk Score (GARS)", and is a tool for the diagnosis of a genetic predisposition for RDS. The use of this test, as pointed out by others, would benefit the medical community by identifying at risk individuals at a very early age. We encourage, in depth work in both animal and human models of addiction. We encourage further exploration of the neurogenetic correlates of the commonalities between food and drug addiction and endorse forward thinking hypotheses like "The Salted Food Addiction Hypothesis".

Adolescent initiation of licit and illicit substance use: Impact of intrauterine exposures and post-natal exposure to violence

Whether intrauterine exposures to alcohol, tobacco, marijuana, or cocaine predispose offspring to substance use in adolescence has not been established. We followed a sample of 149 primarily African American/African Caribbean, urban adolescents, recruited at term birth, until age 16 to investigate intrauterine cocaine exposure (IUCE). We found that in Kaplan-Meier analyses higher levels of IUCE were associated with a greater likelihood of initiation of any substance (licit or illicit), as well as marijuana and alcohol specifically. Adolescent initiation of other illicit drugs and cigarettes were analyzed only in the "any" summary variable since they were used too infrequently to analyze as individual outcomes. In Cox proportional hazard models controlling for intrauterine exposure to alcohol, tobacco, and marijuana and demographic and post-natal covariates, those who experienced heavier IUCE had a greater likelihood of initiation of any substance, and those with lighter intrauterine marijuana exposure had a greater likelihood of initiation of any substance as well as of marijuana specifically. Time-dependent higher levels of exposure to violence between ages of 8 and 16 were also robustly associated with initiation of any licit or illicit substance, and of marijuana, and alcohol particularly.

Risk-taking and the feedback negativity response to loss among at-risk adolescents

Event-related brain potentials were examined in 32 adolescents (50% female) from a high-risk sample, who were exposed to cocaine and other drugs prenatally. Adolescents were selected for extreme high- or low-risk behavior on the Balloon Analog Risk Task, a measure of real-world risk-taking propensity. The feedback error-related negativity (fERN), an event-related potential (ERP) that occurs when an expected reward does not occur, was examined in a game in which choices lead to monetary gains and losses with feedback delayed 1 or 2 s. The fERN was clearly visible in the fronto-central scalp region in this adolescent sample. Feedback type, feedback delay, risk status, and sex were all associated with fERN variability. Monetary feedback also elicited a P300-like component, moderated by delay and sex. Delaying reward feedback may provide a means for studying complementary functioning of dopamine and norepinephrine systems.

Measuring reward with the conditioned place preference (CPP) paradigm: update of the last decade

Conditioned place preference (CPP) continues to be one of the most popular models to study the motivational effects of drugs and non-drug treatments in experimental animals. This is obvious from a steady year-to-year increase in the number of publications reporting the use this model. Since the compilation of the preceding review in 1998, more than 1000 new studies using place conditioning have been published, and the aim of the present review is to provide an overview of these recent publications. There are a number of trends and developments that are obvious in the literature of the last decade. First, as more and more knockout and transgenic animals become available, place conditioning is increasingly used to assess the motivational effects of drugs or non-drug rewards in genetically modified animals. Second, there is a still small but growing literature on the use of place conditioning to study the motivational aspects of pain, a field of pre-clinical research that has so far received little attention, because of the lack of appropriate animal models. Third, place conditioning continues to be widely used to study tolerance and sensitization to the rewarding effects of drugs induced by pre-treatment regimens. Fourth, extinction/reinstatement procedures in place conditioning are becoming increasingly popular. This interesting approach is thought to model certain aspects of relapse to addictive behavior and has previously almost exclusively been studied in drug self-administration paradigms. It has now also become established in the place conditioning literature and provides an additional and technically easy approach to this important phenomenon. The enormous number of studies to be covered in this review prevented in-depth discussion of many methodological, pharmacological or neurobiological aspects; to a large extent, the presentation of data had to be limited to a short and condensed summary of the most relevant findings.

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.

Effect of memantine and CNQX in the acquisition, expression and reinstatement of cocaine-induced conditioned place preference

The present study evaluates the effect of memantine, a non-competitive N-methyl-d-aspartate (NMDA) glutamate receptor antagonist and CNQX, an alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainate receptor antagonist on the rewarding effects of cocaine in mice, using the conditioned place preference (CPP) paradigm. Cocaine-induced CPP was studied pairing this drug with different memantine or CNQX doses during either the acquisition or the expression phase of the procedure. Once CPP was established, and the preference extinguished, reinstatement was induced by a priming dose of cocaine. Both antagonists, which in themselves do not present motivational actions on the preference shown by the animals, abolished the acquisition and expression of the cocaine-induced CPP. Neither of the antagonists precipitated reinstatement of the preference induced by cocaine but memantine blocked the cocaine-primed reinstatement. Our results suggest that cocaine-induced CPP and reinstatement is largely dependent on glutamate neurotransmission, and confer a putative role for memantine among the tools useful for cocaine management and treatment.