Developmental exposure to MDMA (ecstasy) in zebrafish embryos reproduces the neurotoxicity adverse outcome 'lower motor activity' described in humans

The recreational use of MDMA (ecstasy) by pregnant women is associated with impaired neuromotor function in infants, but the Adverse Outcome Pathway behind this effect is not clear yet. We present for the first time the evaluation of developmental neurotoxic (DNT) effects of MDMA in zebrafish embryos. The aim of the study was to determine whether the zebrafish model reproduces the adverse outcome occurring in humans. We have studied the DNT effects of MDMA in zebrafish within a range of 5-250 μM performing different behavioural tests: spontaneous tail-coiling and light-dark locomotor response; after exposing the embryos to 4 different scenarios combining changes in pH, in starting exposure time and exposure duration. In these scenarios we evaluated the effects of MDMA in general embryonic development and compared the concentrations producing them with those inducing specific DNT effects. As a result, we have established the experimental conditions leading to the adverse outcome "lower motor activity" in zebrafish without producing general developmental delay or general toxicity. The experimental condition chosen opens the door to use this model in future mechanistic investigations to better characterize the Adverse Outcome Pathway associated with the adverse effects caused by MDMA prenatal exposure in humans.

A Systematic Review of the MDMA Model to Address Social Impairment in Autism

BACKGROUND

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterised by repetitive behaviours, cognitive rigidity/inflexibility, and social-affective impairment. Unfortunately, no gold-standard treatments exist to alleviate the core socio-behavioural impairments of ASD. Meanwhile, the prosocial empathogen/entactogen 3,4-methylene-dioxy-methamphetamine (MDMA) is known to enhance sociability and empathy in both humans and animal models of psychological disorders.

OBJECTIVE

We review the evidence obtained from behavioural tests across the current literature, showing how MDMA can induce prosocial effects in animals and humans, where controlled experiments were able to be performed.

METHODS

Six electronic databases were consulted. The search strategy was tailored to each database. Only English-language papers were reviewed. Behaviours not screened in this review may have affected the core ASD behaviours studied. Molecular analogues of MDMA have not been investigated.

RESULTS

We find that the social impairments may potentially be alleviated by postnatal administration of MDMA producing prosocial behaviours in mostly the animal model.

CONCLUSION

MDMA and/or MDMA-like molecules appear to be an effective pharmacological treatment for the social impairments of autism, at least in animal models. Notably, clinical trials based on MDMA use are now in progress. Nevertheless, larger and more extended clinical studies are warranted to prove the assumption that MDMA and MDMA-like molecules have a role in the management of the social impairments of autism.

Developmental neurotoxicity of MDMA. A systematic literature review summarized in a putative adverse outcome pathway

The increasing use of illegal drugs by pregnant women causes a public health concern because it is associated with health risks for mothers and their developing children. One of such drugs is MDMA (3,4-methylenedioxymethamphetamine) or ecstasy due to its high consumption in relevant age and sex groups and its adverse effects on human and rodent developing brains. To thoroughly review the current knowledge on the developmentally neurotoxic potential of MDMA we systematically collected and summarized articles investigating developmental neurotoxicity (DNT) of MDMA in humans and animals in vivo and in vitro. In addition, we summarized the findings in a putative adverse outcome pathway (AOP). From an initial 299 articles retrieved from the bibliographic databases Web of Science, PubMed and DART, we selected 39 articles according to inclusion/exclusion criteria for data collection after title/abstract and full text screening. Of these 3 where epidemiological studies, 34 where in vivo studies in mice and rats and 2 were in vitro studies. The three epidemiological studies reported from the same longitudinal study and suggested that MDMA exposure during pregnancy impairs neuromotor function in infants. In rat, postnatal exposure towards MDMA also caused locomotor deficits as well as impaired spatial learning that might be associated with decreased serotonin levels in the hippocampus. In vitro MDMA caused cytotoxicity at high concentrations and effects on the serotonergic and neuritogenic alterations at lower concentrations which are in line with some of the in vivo alterations observed. Considering the adverse outcomes of developmental MDMA described in humans and in rodents we summarized the first putative AOP on developmental compound exposure leading to impaired neuromotor function in children. For generation of this AOP, MDMA exposure was taken as a model compound. In addition, we hypothesized a second AOP involving developmental disturbance of the dopaminergic system. However, further in vitro mechanistic studies are needed to understand the molecular initiating event(s) (MIE) triggering the downstream cascades and obtain consistent evidences causally linking the adverse outcome to effects at the cellular, organ and organism level.

Differential effects of MDMA and cocaine on inhibitory avoidance and object recognition tests in rodents

INTRODUCTION

Drug addiction continues being a major public problem faced by modern societies with different social, health and legal consequences for the consumers. Consumption of psychostimulants, like cocaine or MDMA (known as ecstasy) are highly prevalent and cognitive and memory impairments have been related with the abuse of these drugs.

AIM

The aim of this work was to review the most important data of the literature in the last 10 years about the effects of cocaine and MDMA on inhibitory avoidance and object recognition tests in rodents.

DEVELOPMENT

The object recognition and the inhibitory avoidance tests are popular procedures used to assess different types of memory. We compare the effects of cocaine and MDMA administration in these tests, taking in consideration different factors such as the period of life development of the animals (prenatal, adolescence and adult age), the presence of polydrug consumption or the role of environmental variables. Brain structures involved in the effects of cocaine and MDMA on memory are also described.

CONCLUSIONS

Cocaine and MDMA induced similar impairing effects on the object recognition test during critical periods of lifetime or after abstinence of prolonged consumption in adulthood. Deficits of inhibitory avoidance memory are observed only in adult rodents exposed to MDMA. Psychostimulant abuse is a potential factor to induce memory impairments and could facilitate the development of future neurodegenerative disorders.

Long-term cognitive, emotional and neurogenic alterations induced by alcohol and methamphetamine exposure in adolescent rats

A high proportion of young methamphetamine (MA) users simultaneously consume alcohol. However, the potential neurological and behavioural alterations induced by such a drug combination have not been systematically examined. We studied in adolescent rats the long-term effects of alcohol, MA, and alcohol and MA combined on anxiety-like behaviour, memory, and neurogenesis in the adult hippocampus. Rats received saline, ethanol (ETOH, 1.5g/kg), MA (MA, 2mg/kg), or ethanol and MA combined (ETHOH-MA, 1.5g/kg ethanol plus 2mg/kg MA) via oral gavage, once daily for 5 consecutive days. Open field (OF), elevated plus maze (EPM) and radial arm maze (RAM) tests were conducted following a 15-day withdrawal period. The results showed alterations in exploratory behaviour in the OF in the MA and ETOH-MA groups, and anxiety-like effects in the EPM in all three drug treatment groups. All three drug groups exhibited reference memory deficits in the RAM, but only the combination treatment group displayed alterations in working memory. Both MA and ETOH-MA treatments increased the length of doublecortin (DCX)-void gaps in the dentate gyrus but only ETOH-MA treatment increased the number of such gaps. An increased number and length of DCX-void gaps correlated with decreased exploratory activity in the OF, and impaired working memory in the RAM was associated with an augmented number of gaps. These findings suggest that alterations in adult hippocampal neurogenesis are linked to the persistent cognitive and behavioural deficits produced by alcohol and MA exposure.

Adult Neurogenesis and Psychiatric Disorders

Psychiatric disorders continue to be among the most challenging disorders to diagnose and treat because there is no single genetic or anatomical locus that is causative for the disease. Current treatments are often blunt tools used to ameliorate the most severe symptoms, at the risk of disrupting functional neural systems. There is a critical need to develop new therapeutic strategies that can target circumscribed functional or anatomical domains of pathology. Adult hippocampal neurogenesis may be one such domain. Here, we review the evidence suggesting that adult hippocampal neurogenesis plays a role in emotional regulation and forms of learning and memory that include temporal and spatial memory encoding and context discrimination, and that its dysregulation is associated with psychiatric disorders, such as affective disorders, schizophrenia, and drug addiction. Further, adult neurogenesis has proven to be an effective model to investigate basic processes of neuronal development and converging evidence suggests that aberrant neural development may be an etiological factor, even in late-onset diseases. Constitutive neurogenesis in the hippocampus of the mature brain reflects large-scale plasticity unique to this region and could be a potential hub for modulation of a subset of cognitive and affective behaviors that are affected by multiple psychiatric disorders.

Alteration of Energy Metabolism and Antioxidative Processing in the Hippocampus of Rats Reared in Long-Term Environmental Enrichment

Environmental enrichment (EE) is a typical experimental method that promotes levels of novelty and complexity that enhance experience-dependent neuroplasticity and cognitive behavior function in laboratory animals. Early EE is associated with resilience in the face of later-life challenges. Since increased synaptic activity enhances endogenous neuronal antioxidant defenses, we hypothesized that long-term EE beginning at an early stage may alter the levels of oxidative stress. We investigated global protein expression and oxidative stress in hippocampal proteins from rats nurtured for a 6-month EE beginning in the prenatal period. The analysis of protein expression was carried out using 2-dimensional gel electrophoresis with matrix-associated laser desorption ionization time-of-flight mass spectrometry. Proteins with altered expression were involved in energy metabolism (phosphoglycerate mutase 1, α-enolase isoform 1, adenylate kinase 1, and triose phosphate isomerase) and antioxidant enzymes (superoxide dismutase 1, glutathione S-transferase ω type 1, peroxiredoxin 5, DJ-1, and glial maturation factor β). Using Western blot assays, some of the proteins with altered expression and NADPH oxidase 2 were confirmed to be decreased. Further confirmation was demonstrated with attenuated expression of 7,8-dihydro-8-oxo-deoxyguanine, a DNA oxidative stress marker, in the hippocampus of EE group rats. Our data demonstrate that a long-term EE program beginning in the prenatal and early postnatal phase of development modulates energy metabolism and reduced oxidant stress possibly through enhanced synaptic activity. We provide evidence that EE can be developed as a tool to protect the brain from oxidative stress-induced injury.

Alcohol Interactions with Psychostimulants: An Overview of Animal and Human Studies

Alcohol consumption with psychostimulants is very common among drug addicts. There is little known about the possible pharmacological interactions between alcohol and psychostimulants. Among most commonly co-abused psychostimulants with alcohol are methamphetamine, cocaine, 3,4-methylenedioxymethamphetaminen, and nicotine. Co-abuse of alcohol with psychostimulants can lead to several neurophysiological dysfunctions such as decrease in brain antioxidant enzymes, disruption of learning and memory processes, cerebral hypo-perfusion, neurotransmitters depletion as well as potentiation of drug seeking behaviour. Moreover, co-abuse of alcohol and psychostimulants can lead to increase in heart rate, blood pressure, myocardial oxygen consumption and cellular stress, and the risk of developing different types of cancer. Co-abuse of alcohol with psychostimulants during pregnancy can lead to fetal brain abnormalities. Further studies are needed to investigate the pharmacokinetics, pharmacodynamics, and neurochemical changes on co-abuse of alcohol and psychostimulants.

Motor delays in MDMA (ecstasy) exposed infants persist to 2 years

BACKGROUND

Recreational use of 3,4 methylenedioxymethamphetamine (ecstasy, MDMA) is increasing worldwide. Its use by pregnant women causes concern due to potentially harmful effects on the developing fetus. MDMA, an indirect monoaminergic agonist and reuptake inhibitor, affects the serotonin and dopamine systems. Preclinical studies of fetal exposure demonstrate effects on learning, motor behavior, and memory. In the first human studies, we found prenatal MDMA exposure related to poorer motor development in the first year of life. In the present study we assessed the effects of prenatal exposure to MDMA on the trajectory of child development through 2 years of age. We hypothesized that exposure would be associated with poorer mental and motor outcomes.

MATERIALS AND METHODS

The DAISY (Drugs and Infancy Study, 2003-2008) employed a prospective longitudinal cohort design to assess recreational drug use during pregnancy and child outcomes in the United Kingdom. Examiners masked to drug exposures followed infants from birth to 4, 12, 18, and 24 months of age. MDMA, cocaine, alcohol, tobacco, cannabis, and other drugs were quantified through a standardized clinical interview. The Bayley Scales (III) of Mental (MDI) and Motor (PDI) Development and the Behavior Rating Scales (BRS) were primary outcome measures. Statistical analyses included a repeated measures mixed model approach controlling for multiple confounders.

RESULTS

Participants were pregnant women volunteers, primarily white, of middle class socioeconomic status, average IQ, with some college education, in stable partner relationships. Of 96 women enrolled, children of 93 had at least one follow-up assessment and 81 (87%) had ≥ two assessments. Heavier MDMA exposure (M=1.3±1.4 tablets per week) predicted lower PDI (p<.002), and poorer BRS motor quality from 4 to 24 months of age, but did not affect MDI, orientation, or emotional regulation. Children with heavier exposure were twice as likely to demonstrate poorer motor quality as lighter and non-exposed children (O.R.=2.2, 95%, CI=1.02-4.70, p<.05).

DISCUSSION

Infants whose mothers reported heavier MDMA use during pregnancy had motor delays from 4 months to two years of age that were not attributable to other drug or lifestyle factors. Women of child bearing age should be cautioned about the use of MDMA and MDMA-exposed infants should be screened for motor delays and possible intervention.

Impaired ILK Function Is Associated with Deficits in Hippocampal Based Memory and Synaptic Plasticity in a FASD Rat Model

Fetal Alcohol Spectrum Disorder (FASD) is an umbrella term that encompasses a wide range of anatomical and behavioral problems in children who are exposed to alcohol during the prenatal period. There is no effective treatment for FASD, because of lack of complete characterization of the cellular and molecular mechanisms underlying this condition. Alcohol has been previously characterized to affect integrins and growth factor signaling receptors. Integrin Linked Kinase (ILK) is an effector of integrin and growth-factor signaling which regulates various signaling processes. In FASD, a downstream effector of ILK, Glycogen Synthase Kinase 3β (GSK3β) remains highly active (reduced Ser9 phosphorylation). GSK3β has been known to modulate glutamate receptor trafficking and channel properties. Therefore, we hypothesize that the cognitive deficits accompanying FASD are associated with impairments in the ILK signaling pathway. Pregnant Sprague Dawley rats consumed a "moderate" amount of alcohol throughout gestation, or a calorie-equivalent sucrose solution. Contextual fear conditioning was used to evaluate memory performance in 32-33-day-old pups. Synaptic plasticity was assessed in the Schaffer Collateral pathway, and hippocampal protein lysates were used to evaluate ILK signaling. Alcohol exposed pups showed impaired contextual fear conditioning, as compared to control pups. This reduced memory performance was consistent with decrease in LTP as compared to controls. Hippocampal ILK activity and GSK3β Ser21/9 phosphorylation were significantly lower in alcohol-exposed pups than controls. Increased synaptic expression of GluR2 AMPA receptors was observed with immunoprecipitation of post-synaptic density protein 95 (PSD95). Furthermore, immunoprecipitation of ILK revealed a decreased interaction with GluR2. The ILK pathway appears to play a significant role in memory and synaptic plasticity impairments in FASD rats. These impairments appear to be mediated by reduced GSK3β regulation and increased synaptic stabilization of the calcium-impermeable GluR2 AMPA receptors.

Developmental consequences of fetal exposure to drugs: what we know and what we still must learn

Most drugs of abuse easily cross the placenta and can affect fetal brain development. In utero exposures to drugs thus can have long-lasting implications for brain structure and function. These effects on the developing nervous system, before homeostatic regulatory mechanisms are properly calibrated, often differ from their effects on mature systems. In this review, we describe current knowledge on how alcohol, nicotine, cocaine, amphetamine, Ecstasy, and opiates (among other drugs) produce alterations in neurodevelopmental trajectory. We focus both on animal models and available clinical and imaging data from cross-sectional and longitudinal human studies. Early studies of fetal exposures focused on classic teratological methods that are insufficient for revealing more subtle effects that are nevertheless very behaviorally relevant. Modern mechanistic approaches have informed us greatly as to how to potentially ameliorate the induced deficits in brain formation and function, but conclude that better delineation of sensitive periods, dose-response relationships, and long-term longitudinal studies assessing future risk of offspring to exhibit learning disabilities, mental health disorders, and limited neural adaptations are crucial to limit the societal impact of these exposures.