Neuropathology of the cerebral cortex observed in a range of animal models of prenatal cocaine exposure may reflect alterations in genes involved in the Wnt and cadherin systems

Epigenetic Studies for Evaluation of NPS Toxicity: Focus on Synthetic Cannabinoids and Cathinones

In the recent decade, numerous new psychoactive substances (NPSs) have been added to the illicit drug market. These are synthetized to mimic the effects of classic drugs of abuse (i.e., cannabis, cocaine, etc.), with the purpose of bypassing substance legislations and increasing the pharmacotoxicological effects. To date, research into the acute pharmacological effects of new NPSs is ongoing and necessary in order to provide an appropriate contribution to public health. In fact, multiple examples of NPS-related acute intoxication and mortality have been recorded in the literature. Accordingly, several in vitro and in vivo studies have investigated the pharmacotoxicological profiles of these compounds, revealing that they can cause adverse effects involving various organ systems (i.e., cardiovascular, respiratory effects) and highlighting their potential increased consumption risks. In this sense, NPSs should be regarded as a complex issue that requires continuous monitoring. Moreover, knowledge of long-term NPS effects is lacking. Because genetic and environmental variables may impact NPS responses, epigenetics may aid in understanding the processes behind the harmful events induced by long-term NPS usage. Taken together, “pharmacoepigenomics” may provide a new field of combined study on genetic differences and epigenetic changes in drug reactions that might be predictive in forensic implications.

The cellular basis of fetal endoplasmic reticulum stress and oxidative stress in drug-induced neurodevelopmental deficits

Prenatal substance exposure is a growing public health concern worldwide. Although the opioid crisis remains one of the most prevalent addiction problems in our society, abuse of cocaine, methamphetamines, and other illicit drugs, particularly amongst pregnant women, are nonetheless significant and widespread. Evidence demonstrates prenatal drug exposure can affect fetal brain development and thus can have long-lasting impact on neurobehavioral and cognitive performance later in life. In this review, we highlight research examining the most prevalent drugs of abuse and their effects on brain development with a focus on endoplasmic reticulum stress and oxidative stress signaling pathways. A thorough exploration of drug-induced cellular stress mechanisms during prenatal brain development may provide insight into therapeutic interventions to combat effects of prenatal drug exposure.

Pentazocine Protects SN4741 Cells Against MPP+-Induced Cell Damage via Up-Regulation of the Canonical Wnt/β-Catenin Signaling Pathway

The Wnt/β-catenin signaling pathway has been linked to many neurodegenerative diseases including Parkinson’s disease (PD). A glycoprotein named Dickkopf-1 (Dkk1) can combine with the receptor complex on cell membrane to inhibit Wnt/β-catenin signaling. Opioids, a series of compounds including morphine, fentanyl and pentazocine, have been reported to contribute to the up-regulation of Wnt/β-catenin signaling. Naloxone is an antagonist that has been used as an antidote to opioids through mu-opioid receptor. 1-methyl-4-phenylpyridinium (MPP⁺), which serves as a selective toxin for dopaminergic neurons, has been used to create experimental models of PD. In our study, we examined the protective effects of pentazocine against MPP⁺-induced cell death in the nigral dopaminergic cell line, SN4741 and tried to elucidate the molecular mechanisms underlying such protective effects. The data showed that pretreatment with pentazocine significantly rescued the SN4741 cell against MPP⁺. Moreover, the MPP⁺-exposed SN4741 cells exhibited a down-regulation of β-catenin, which could be restored by treatment with pentazocine. However, Dkk1 but not naloxonewas associated with the abrogation of protective effect of pentazocine. These results suggest that pentazocine alleviates MPP⁺-induced SN4741 cells apoptosis via the up-regulation of canonical Wnt/β-catenin signaling.

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.

Models of cortical malformation--Chemical and physical

Pharmaco-resistant epilepsies, and also some neuropsychiatric disorders, are often associated with malformations in hippocampal and neocortical structures. The mechanisms leading to these cortical malformations causing an imbalance between the excitatory and inhibitory system are largely unknown. Animal models using chemical or physical manipulations reproduce different human pathologies by interfering with cell generation and neuronal migration. The model of in utero injection of methylazoxymethanol (MAM) acetate mimics periventricular nodular heterotopia. The freeze lesion model reproduces (poly)microgyria, focal heterotopia and schizencephaly. The in utero irradiation model causes microgyria and heterotopia. Intraperitoneal injections of carmustine 1-3-bis-chloroethyl-nitrosurea (BCNU) to pregnant rats produces laminar disorganization, heterotopias and cytomegalic neurons. The ibotenic acid model induces focal cortical malformations, which resemble human microgyria and ulegyria. Cortical dysplasia can be also observed following prenatal exposure to ethanol, cocaine or antiepileptic drugs. All these models of cortical malformations are characterized by a pronounced hyperexcitability, few of them also produce spontaneous epileptic seizures. This dysfunction results from an impairment in GABAergic inhibition and/or an increase in glutamatergic synaptic transmission. The cortical region initiating or contributing to this hyperexcitability may not necessarily correspond to the site of the focal malformation. In some models wide-spread molecular and functional changes can be observed in remote regions of the brain, where they cause pathophysiological activities. This paper gives an overview on different animal models of cortical malformations, which are mostly used in rodents and which mimic the pathology and to some extent the pathophysiology of neuronal migration disorders associated with epilepsy in humans.

WNT signaling underlies the pathogenesis of neuropathic pain in rodents

Treating neuropathic pain is a major clinical challenge, and the underlying mechanisms of neuropathic pain remain elusive. We hypothesized that neuropathic pain-inducing nerve injury may elicit neuronal alterations that recapitulate events that occur during development. Here, we report that WNT signaling, which is important in developmental processes of the nervous system, plays a critical role in neuropathic pain after sciatic nerve injury and bone cancer in rodents. Nerve injury and bone cancer caused a rapid-onset and long-lasting expression of WNTs, as well as activation of WNT/frizzled/β-catenin signaling in the primary sensory neurons, the spinal dorsal horn neurons, and astrocytes. Spinal blockade of WNT signaling pathways inhibited the production and persistence of neuropathic pain and the accompanying neurochemical alterations without affecting normal pain sensitivity and locomotor activity. WNT signaling activation stimulated production of the proinflammatory cytokines IL-18 and TNF-α and regulated the NR2B glutamate receptor and Ca2+-dependent signals through the β-catenin pathway in the spinal cord. These findings indicate a critical mechanism underlying the pathogenesis of neuropathic pain and suggest that targeting the WNT signaling pathway may be an effective approach for treating neuropathic pain, including bone cancer pain.

Effects of cocaine and withdrawal on the mouse nucleus accumbens transcriptome

Genetic association studies, pharmacological investigations and analysis of mice-lacking individual genes have made it clear that Cocaine administration and Withdrawal have a profound impact on multiple neurotransmitter systems. The GABAergic medium spiny neurons of the nucleus accumbens (NAc) exhibit changes in the expression of genes encoding receptors for glutamate and in the signaling pathways triggered by dopamine binding to G-protein-coupled dopamine receptors. Deep sequence analysis provides a sensitive, quantitative and global analysis of the effects of Cocaine on the NAc transcriptome. RNA prepared from the NAc of adult male mice receiving daily injections of Saline or Cocaine, or Cocaine followed by a period of Withdrawal, was used for high-throughput sequence analysis. Changes were validated by quantitative polymerase chain reaction or Western blot. On the basis of pathway analysis, a preponderance of the genes affected by Cocaine and Withdrawal was involved in the cadherin, heterotrimeric G-protein and Wnt signaling pathways. Distinct subsets of cadherins and protocadherins exhibited a sustained increase or decrease in expression. Sustained down-regulation of several heterotrimeric G-protein β- and γ-subunits was observed. In addition to altered expression of receptors for small molecule neurotransmitters, neuropeptides and endocannabinoids, changes in the expression of plasma membrane transporters and vesicular neurotransmitter transporters were also observed. The effects of chronic Cocaine and Withdrawal on the expression of genes essential to cholinergic, glutamatergic, GABAergic, peptidergic and endocannabinoid signaling are as profound as their effects on dopaminergic transmission. Simultaneous targeting of multiple Withdrawal-specific changes in gene expression may facilitate development of new therapeutic approaches that are better able to prevent relapse.

Gene expression profiling reveals distinct cocaine-responsive genes in human fetal CNS cell types

OBJECTIVES

Prenatal exposure to cocaine causes cytoarchitectural alterations in the developing neocortex. Previously, we reported that cocaine inhibits neural progenitor cell proliferation through oxidative endoplasmic reticulum stress and consequent down-regulation of cyclin A, whereas cyclin A expression was increased in astrocytes. In the present study, cell type-specific responses to cocaine were further explored.

METHODS

Gene expression profiles were examined in five types of cells obtained from the human fetal cerebral cortex at 20 weeks gestation. Cells were treated with 100 µM cocaine in vitro for 24 hr, followed by gene expression analysis using a human neural/stem cell/drug abuse-focused cDNA array, with verification by quantitative real-time RT-PCR.

RESULTS

Cocaine influenced transcription of distinct categories of genes in a cell type-specific manner. Cocaine down-regulated cytoskeleton-related genes including ezrin, γ2 actin, α3d tubulin and α8 tubulin in neural and/or A2B5+ progenitor cells. In contrast, cocaine modulated immune and cell death-related genes in microglia and astrocytes. In microglia, cocaine up-regulated the immunoregulatory and pro-apoptotic genes IL-1β and BAX. In astrocytes, cocaine down-regulated the immune response gene glucocorticoid receptor and up-regulated the anti-apoptotic genes 14-3-3 ε and HVEM. Therefore, cell types comprising the developing neocortex show differential responses to cocaine.

CONCLUSIONS

These data suggest that cocaine causes cytoskeletal abnormalities leading to disturbances in neural differentiation and migration in progenitor cells, while altering immune and apoptotic responses in glia. Understanding the mechanisms of cocaine's effects on human CNS cells may help in the development of therapeutic strategies to prevent or ameliorate cocaine-induced impairments in fetal brain development.

NMDA receptor activation stimulates transcription-independent rapid wnt5a protein synthesis via the MAPK signaling pathway

Wnt proteins are emerging key regulators of the plasticity and functions of adult brains. However, the mechanisms by which the expression of Wnt proteins is regulated in neurons are unclear. Using cortical primary cultures, we show here that activation of NMDA receptors (NMDARs) induces rapid Wnt5a protein synthesis and secretion. This NMDAR-regulated Wnt5a synthesis does not require transcription and is a result of activity-dependent translation. We also show that NMDAR-regulated Wnt5a translation depends on MAPK signaling but not mTOR signaling. Our findings suggest that the synaptic activity of CNS neurons activates NMDARs, which in turn stimulate translation from stored Wnt5a mRNA via the MAPK signaling pathway.

Methamphetamine and HIV-1 Tat down regulate β-catenin signaling: implications for methampetamine abuse and HIV-1 co-morbidity

Methamphetamine (Meth) abuse exacerbates HIV-1-associated neurocognitive disorders (HAND). The underlying mechanism for this effect is not entirely clear but likely involves cooperation between Meth and HIV-1 virotoxins, such as the transactivator of transcription, Tat. HIV-1 Tat mediates damage in the CNS by inducing inflammatory processes including astrogliosis. Wnt/β-catenin signaling regulates survival processes for both neurons and astrocytes. Here, we evaluated the impact of Meth on the Wnt/β-catenin pathway in astrocytes transfected with Tat. Meth and Tat downregulated Wnt/β-catenin signaling by >50%, as measured by TOPflash reporter activity in both an astrocytoma cell line and primary human fetal astrocytes. Meth and Tat also downregulated LEF-1 transcript by >30%. LEF-1 is a key partner of β-catenin to regulate cognate gene expression. Interestingly, estrogen, which induces β-catenin signaling in a cell-type specific manner, at physiological concentrations of 1.5 and 3 nM normalized individual Meth and Tat effects on β-catenin signaling but not their combined effects. These findings suggest that Meth and Tat likely exert different mechanisms to mediate down regulation of β-catenin signaling. The consequences of which may contribute to the pathophysiologic effects of HIV-1 and Meth co-morbidity in the CNS.

Dopamine, cocaine and the development of cerebral cortical cytoarchitecture: a review of current concepts

Exposure of the developing fetus to cocaine produces lasting adverse effects on brain structure and function. Animal models show that cocaine exerts its effects by interfering with monoamine neurotransmitter function and that dopamine is cocaine's principal monoamine target in the fetal brain. This review will examine the role of dopamine receptor signaling in the regulation of normal development of the cerebral cortex, the seat of higher cognitive functions, and discuss whether dopamine receptor signaling mechanisms are the principal mediators of cocaine's deleterious effects on the ontogeny of cerebral cortical cytoarchitecture.

Gene profiling the response to repeated cocaine self-administration in dorsal striatum: a focus on circadian genes

Alterations in gene expression in the dorsal striatum caused by chronic cocaine exposure have been implicated in the long-term behavioral changes associated with cocaine addiction. To gain further insight into the molecular alterations that occur as a result of cocaine self-administration, we conducted a microarray analysis of gene expression followed by bioinformatic gene network analysis that allowed us to identify adaptations at the level of gene expression as well as into interconnected networks. Changes in gene expression were examined in the dorsal striatum of rats 1 day after they had self-administered cocaine for 7 days under a 24-h access, discrete trial paradigm (averaging 98 mg/kg/day). Here we report the regulation of the circadian genes Clock, Bmal1, Cryptochrome1, Period2, as well as several genes that are regulated by/associated with the circadian system (i.e., early growth response 1, dynorphin). We also observed regulation of other relevant genes (i.e., Nur77, beta catenin). These changes were then linked to curated pathways and formulated networks which identified circadian rhythm processes as affected by cocaine self-administration. These data strongly suggest involvement of circadian-associated genes in the brain's response to cocaine and may contribute to an understanding of addictive behavior including disruptions in sleep and circadian rhythmicity.

Maternal cocaine administration in mice alters DNA methylation and gene expression in hippocampal neurons of neonatal and prepubertal offspring

Previous studies documented significant behavioral changes in the offspring of cocaine-exposed mothers. We now explore the hypothesis that maternal cocaine exposure could alter the fetal epigenetic machinery sufficiently to cause lasting neurochemical and functional changes in the offspring. Pregnant CD1 mice were administered either saline or 20 mg/kg cocaine twice daily on gestational days 8–19. Male pups from each of ten litters of the cocaine and control groups were analyzed at 3 (P3) or 30 (P30) days postnatum. Global DNA methylation, methylated DNA immunoprecipitation followed by CGI² microarray profiling and bisulfite sequencing, as well as quantitative real-time RT-PCR gene expression analysis, were evaluated in hippocampal pyramidal neurons excised by laser capture microdissection. Following maternal cocaine exposure, global DNA methylation was significantly decreased at P3 and increased at P30. Among the 492 CGIs whose methylation was significantly altered by cocaine at P3, 34% were hypermethylated while 66% were hypomethylated. Several of these CGIs contained promoter regions for genes implicated in crucial cellular functions. Endogenous expression of selected genes linked to the abnormally methylated CGIs was correspondingly decreased or increased by as much as 4–19-fold. By P30, some of the cocaine-associated effects at P3 endured, reversed to opposite directions, or disappeared. Further, additional sets of abnormally methylated targets emerged at P30 that were not observed at P3. Taken together, these observations indicate that maternal cocaine exposure during the second and third trimesters of gestation could produce potentially profound structural and functional modifications in the epigenomic programs of neonatal and prepubertal mice.

Cocaine exposure in vitro induces apoptosis in fetal locus coeruleus neurons through TNF-alpha-mediated induction of Bax and phosphorylated c-Jun NH(2)-terminal kinase

Cocaine exposure results in aberrant outgrowth and decreased survival for locus coeruleus (LC), a noradrenergic population of neurons that putatively regulates attentional function; however, the underlying mechanisms for these events are not known. We previously showed that cocaine exposure in vitro activates pro-apoptotic Bax, caspase-9, and caspase-3 in LC neurons dissected from embryonic day 14 rats, implicating that apoptosis may be orchestrated via signal transduction events. In the current study in vitro, we examined upstream events to determine the role of the pro-inflammatory cytokine, tumor necrosis factor alpha (TNF-alpha), on LC signal transduction, because cocaine exposure to LC neurons triggered TNF-alpha expression at 30 min as measured by ELISA. Exposure of LC neurons to recombinant-TNF-alpha resulted in decreased metabolic activity, an indicator of reduced neuron viability [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay], and increased apoptosis (terminal deoxynucleotidyl transferase-mediated DNA nick end labeling assay). Pro-apoptotic caspase-3 was induced by cocaine starting at 30 min. Recombinant-TNF-alpha induced caspase-3 activity earlier than cocaine (15 and 20 min). The caspase-3 levels were significantly reduced when cocaine and TNF-alpha were combined with neutralizing-TNF-alpha (nTNF-alpha), respectively. Further, cocaine alone elevated phospho-p38-mitogen-activated protein kinases that persisted when combined with nTNF-alpha. However, both cocaine and TNF-alpha independently increased phospho-c-Jun NH(2)-terminal kinase and Bax levels at concurrent time periods (30 min and 1 h), and this elevation was attenuated in the presence of nTNF-alpha. These simultaneous molecular events triggered by cocaine and TNF-alpha implicate a potential apoptotic signal transduction pathway via induction of phospho-c-Jun NH(2)-terminal kinase and Bax that may lead to caspase-3 activation and apoptosis in cocaine-exposed fetal LC neurons.

Genomewide suggestive linkage of opioid dependence to chromosome 14q

The genetic predisposition to addiction to opioids and other substances is transmitted as a complex genetic trait, which investigators are attempting to characterize using genetic linkage and association. We now report a high-density genome-wide linkage study of opioid dependence. We ascertained 305 DSM-IV opioid dependent affected sibling pairs from an ethnically mixed population of methadone maintained subjects and genotyped their DNA using Affymetrix 10K v2 arrays. Analysis with MERLIN identified a region on chromosome 14q with a non-parametric lod (NPL) of 3.30. Secondary analyses indicated that this locus was relatively specific to the self-identified Puerto Rican subset, as the NPL increased from 3.30 to 5.00 (NPL(Caucasian) = 0.05 and NPL(African Amer.) = 0.15). The 14q peak encompasses the NRXN3 gene (neurexin 3), which was previously identified as a potential candidate gene for addiction. Secondary analyses also identified several regions with gender-specific NPL scores greater than 2.00. The most significant was a peak on (10q) that increased from 0.90 to 3.22 when only males were considered (NPL(female) = 0.05). Our linkage data suggest specific chromosomal loci for future fine-mapping genetic analysis and support the hypothesis that ethnic and gender specific genes underlie addiction susceptibility.

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.

Activity-dependent Synaptic Wnt Release Regulates Hippocampal Long Term Potentiation

Wnts are important for various developmental and oncogenic processes. Here we show that Wnt signaling functions at synapses in hippocampal neurons. Tetanic stimulations induce N-methyl-d-aspartate receptor-dependent synaptic Wnt3a release, nuclear beta-catenin accumulations, and the activation of Wnt target genes. Suppression of Wnt signaling impairs long term potentiation. Conversely, activation of Wnt signaling facilitates long term potentiation. These findings suggest that Wnt signaling plays a critical role in regulating synaptic plasticity.

Consequences of paternal cocaine exposure in mice

The present study examined the potential neuroteratological effects of paternal cocaine (COC) exposure using the novel mouse model of inhalational drug administration. In this model, mice were trained to self-administer COC in multi-hour daily inhalation sessions reminiscent of crack binges. The controls included males pair-fed with COC-inhaling animals as well as ad-lib-fed males. All males were bred with drug-naive females. The newborn pups sired by COC-inhaling males had a reduced biparietal head diameter, suggesting a decreased cerebral volume. When the pups reached adulthood, their sustained visuo-spatial attention and spatial working memory were tested using a 5-arm maze paradigm. During the attention tests, the percentage of correct trials at the shortest stimulus duration employed in the study (0.5 s) was significantly lower for the male offspring of COC-inhaling fathers as compared to the offspring of both pair-fed and ad-lib-fed controls. For the females sired by COC-inhaling fathers, the deficit was observed at light stimulus durations of 0.5 and 0.75 s. Also, during the working memory tests, the male offspring of COC-inhaling fathers required more sessions than the offspring of either pair-fed or ad-lib-fed fathers to reach the selected criterion at retention intervals of 16 min and longer. The impairment of working memory in female offspring of COC-inhaling fathers was even stronger, as the offspring needed more sessions to reach the criterion as compared to their control counterparts, even at retention intervals as short as 4 min. These findings suggest that paternal COC abuse prior to coitus may impact the development of the offspring, particularly if they are females. We further showed that chronic COC exposure in male mice does not result in substantial breakage of spermatozoal DNA, but significantly alters expression of DNA methyltransferases 1 and 3a in the germ cell-rich seminiferous tubules of the testis. Since these enzymes are essential for generating and maintaining parental gene imprinting in germ cells, our observations point to an intriguing possibility that COC may cause paternally induced neuroteratological effects by interfering with gene-imprinting patterns in male gametes.

Specificity of prenatal cocaine on inhibition of locus coeruleus neurite outgrowth

Prenatal cocaine exposure induces alterations in attentional function that presumably involve locus coeruleus noradrenergic neurons and their projections. Previous reports indicate that embryonic rat locus coeruleus neurons exposed to cocaine, both in vitro and in vivo, showed in decreased cell survival and inhibition of neurite outgrowth, and that the effects were most deleterious during early gestation. The present study performed in vitro addressed the specificity of the inhibitory effects of cocaine by comparing locus coeruleus neurite formation and extension to that of dopaminergic substantia nigra neurons following exposure to a physiologically-relevant dose of cocaine (500 ng/ml, two times a day, for four days) during peak neuritogenesis. Following cocaine treatment, immunocytochemistry (anti-norepinephrine antibody to locus coeruleus; anti-tyrosine hydroxylase antibody to substantia nigra) and image analysis were performed to measure a variety of neurite outgrowth parameters. For locus coeruleus neurons, cocaine treatment decreased the 1) number of cells initiating neurites [P<0.001], 2) mean number [P<0.05] and length of neurites [P<0.0001], 3) mean number [P<0.0016] and length of branched neurites [P<0.0006], and 4) mean length of the longest neurites [P<0.0001]. In comparison, substantia nigra neurons were not significantly affected by cocaine for any of the parameters examined. More importantly, a significant interaction between cocaine treatment and brain region was observed [P<0.0002] indicating greater vulnerability of locus coeruleus, relative to substantia nigra neurons, to cocaine exposure. These data support our hypothesis that cocaine targets the noradrenergic system by negatively regulating locus coeruleus neuronal outgrowth, which likely affects pathfinding, synaptic connectivity, and ultimately attentional behavior in cocaine-exposed offspring.

Inhalational model of cocaine exposure in mice: neuroteratological effects

We developed a novel inhalation-based mouse model of prenatal cocaine exposure. This model approximates cocaine abuse via smoking, the preferred route of cocaine administration by heavy drug users. The model is also characterized by (i) absence of procedural stress from drug administration, (ii) long-term drug exposure starting weeks before pregnancy and continuing throughout the entire gestation, and (iii) self-administration of cocaine in multi-hour daily sessions reminiscent of drug binges, which allows animals to set up the levels of their own drug consumption. The offspring of female mice inhaling cocaine in our model displayed no gross alterations in their cortical cytoarchitecture. These offspring, however, showed significant impairments in sustained attention and spatial working memory. We hope that the introduction of the present model will lead to a significant increase in our understanding of outcomes of prenatal cocaine exposure.