The distribution of 3,4-methylenedioxymethamphetamine "Ecstasy"-induced c-fos expression in rat brain

Hallucinogenic drugs and their potential for treating fear-related disorders: Through the lens of fear extinction

Fear-related disorders, mainly phobias and post-traumatic stress disorder, are highly prevalent, debilitating disorders that pose a significant public health problem. They are characterized by aberrant processing of aversive experiences and dysregulated fear extinction, leading to excessive expression of fear and diminished quality of life. The gold standard for treating fear-related disorders is extinction-based exposure therapy (ET), shown to be ineffective for up to 35% of subjects. Moreover, ET combined with traditional pharmacological treatments for fear-related disorders, such as selective serotonin reuptake inhibitors, offers no further advantage to patients. This prompted the search for ways to improve ET outcomes, with current research focused on pharmacological agents that can augment ET by strengthening fear extinction learning. Hallucinogenic drugs promote reprocessing of fear-imbued memories and induce positive mood and openness, relieving anxiety and enabling the necessary emotional engagement during psychotherapeutic interventions. Mechanistically, hallucinogens induce dynamic structural and functional neuroplastic changes across the fear extinction circuitry and temper amygdala's hyperreactivity to threat-related stimuli, effectively mitigating one of the hallmarks of fear-related disorders. This paper provides the first comprehensive review of hallucinogens' potential to alleviate symptoms of fear-related disorders by focusing on their effects on fear extinction and the underlying molecular mechanisms. We overview both preclinical and clinical studies and emphasize the advantages of hallucinogenic drugs over current first-line treatments. We highlight 3,4-methylenedioxymethamphetamine and ketamine as the most effective therapeutics for fear-related disorders and discuss the potential molecular mechanisms responsible for their potency with implications for improving hallucinogen-assisted psychotherapy.

3,4-Methylenedioxy methamphetamine, synthetic cathinones and psychedelics: From recreational to novel psychotherapeutic drugs

The utility of classical drugs used to treat psychiatric disorders (e.g., antidepressants, anxiolytics) is often limited by issues of lack of efficacy, delayed onset of action or side effects. Psychoactive substances have a long history of being used as tools to alter consciousness and as a gateway to approach the unknown and the divinities. These substances were initially obtained from plants and animals and more recently by chemical synthesis, and its consumption evolved toward a more recreational use, leading to drug abuse-related disorders, trafficking, and subsequent banning by the authorities. However, these substances, by modulation of certain neurochemical pathways, have been proven to have a beneficial effect on some psychiatric disorders. This evidence obtained under medically controlled conditions and often associated with psychotherapy, makes these substances an alternative to conventional medicines, to which in many cases the patient does not respond properly. Such disorders include post-traumatic stress disease and treatment-resistant depression, for which classical drugs such as MDMA, ketamine, psilocybin and LSD, among others, have already been clinically tested, reporting successful outcomes. The irruption of new psychoactive substances (NPS), especially during the last decade and despite their recreational and illicit uses, has enlarged the library of substances with potential utility on these disorders. In fact, many of them were synthetized with therapeutic purposes and were withdrawn for concrete reasons (e.g., adverse effects, improper pharmacological profile). In this review we focus on the basis, existing evidence and possible use of synthetic cathinones and psychedelics (specially tryptamines) for the treatment of mental illnesses and the properties that should be found in NPS to obtain new therapeutic compounds.

The Paraventricular Thalamus as a Critical Node of Motivated Behavior via the Hypothalamic-Thalamic-Striatal Circuit

In this review, we highlight evidence that supports a role for the paraventricular nucleus of the thalamus (PVT) in motivated behavior. We include a neuroanatomical and neurochemical overview, outlining what is known of the cellular makeup of the region and its most prominent afferent and efferent connections. We discuss how these connections and distinctions across the anterior-posterior axis correspond to the perceived function of the PVT. We then focus on the hypothalamic-thalamic-striatal circuit and the neuroanatomical and functional placement of the PVT within this circuit. In this regard, the PVT is ideally positioned to integrate information regarding internal states and the external environment and translate it into motivated actions. Based on data that has emerged in recent years, including that from our laboratory, we posit that orexinergic (OX) innervation from the lateral hypothalamus (LH) to the PVT encodes the incentive motivational value of reward cues and thereby alters the signaling of the glutamatergic neurons projecting from the PVT to the shell of the nucleus accumbens (NAcSh). The PVT-NAcSh pathway then modulates dopamine activity and resultant cue-motivated behaviors. As we and others apply novel tools and approaches to studying the PVT we will continue to refine the anatomical, cellular, and functional definitions currently ascribed to this nucleus and further elucidate its role in motivated behaviors.

The paraventricular nucleus of the thalamus: an integrative node underlying homeostatic behavior

Early anatomical evidence suggested that the paraventricular nucleus of the thalamus (PVT) regulates arousal, as well as emotional and motivated behaviors. We discuss recent studies using modern techniques which now confirm and expand the involvement of the rodent PVT in these functions. Despite the emerging notion that the PVT is implicated in various behavioral processes, a recurrent theme is that activity in this brain region depends on internal state information arriving from the hypothalamus and brainstem, and is influenced by prior experience. We propose that the primary function of the PVT is to detect homeostatic challenges by integrating information about prior experiences, competing needs, and internal state to guide adaptive behavioral responses aimed at restoring homeostasis.

New designer phenethylamines 2C-C and 2C-P have abuse potential and induce neurotoxicity in rodents

2C (2C-x) is the general name for the family of phenethylamines containing two methoxy groups at the 2 and 5 positions of the benzene ring. The abuse of 2C family drugs has grown rapidly, although the abuse potential and neurotoxic properties of 2C drugs have not yet been fully investigated. In this study, we investigated the abuse potential and neurotoxicity of 4-chloro-2,5-dimethoxyphenethylamine (2C-C) and 2,5-dimethoxy-4-propylphenethylamine (2C-P). We found that 2C-C and 2C-P produced conditioned place preference in a dose-dependent manner in mice, and increased self-administration in rats, suggesting that 2C-C and 2C-P have abuse potential. To investigate the neurotoxicity of 2C-C and 2C-P, we examined motor performance and memory impairment after high doses of 2C-C and 2C-P. High doses of 2C-C and 2C-P decreased locomotor activity, rota-rod performance, and lower Y-maze test, novel objective recognition test, and passive avoidance test scores. We also observed that 2C-C and 2C-P affected expression levels of the D1 dopamine receptor, D2 dopamine receptor, dopamine transporter, and phospho-dopamine transporter in the nucleus accumbens and the medial prefrontal cortex, and increased c-Fos immuno-positive cells in the nucleus accumbens. Moreover, high doses of 2C-C and 2C-P induced microglial activation, which is involved in the inflammatory reaction in the striatum. These results suggest that 2C-C and 2C-P have abuse potential by affecting dopaminergic signaling and induce neurotoxicity via initiating neuroinflammation at high doses.

The cerebellum under stress

Stress-related psychiatric conditions are one of the main causes of disability in developed countries. They account for a large portion of resource investment in stress-related disorders, become chronic, and remain difficult to treat. Research on the neurobehavioral effects of stress reveals how changes in certain brain areas, mediated by a number of neurochemical messengers, markedly alter behavior. The cerebellum is connected with stress-related brain areas and expresses the machinery required to process stress-related neurochemical mediators. Surprisingly, it is not regarded as a substrate of stress-related behavioral alterations, despite numerous studies that show cerebellar responsivity to stress. Therefore, this review compiles those studies and proposes a hypothesis for cerebellar function in stressful conditions, relating it to stress-induced psychopathologies. It aims to provide a clearer picture of stress-related neural circuitry and stimulate cerebellum-stress research. Consequently, it might contribute to the development of improved treatment strategies for stress-related disorders.

Transient inactivation of the paraventricular nucleus of the thalamus enhances cue-induced reinstatement in goal-trackers, but not sign-trackers

RATIONALE

The paraventricular nucleus of the thalamus (PVT) has been shown to mediate cue-motivated behaviors, such as sign- and goal-tracking, as well as reinstatement of drug-seeking behavior. However, the role of the PVT in mediating individual variation in cue-induced drug-seeking behavior remains unknown.

OBJECTIVES

This study aimed to determine if inactivation of the PVT differentially mediates cue-induced drug-seeking behavior in sign-trackers and goal-trackers.

METHODS

Rats were characterized as sign-trackers (STs) or goal-trackers (GTs) based on their Pavlovian conditioned approach behavior. Rats were then exposed to 15 days of cocaine self-administration, followed by a 2-week forced abstinence period and then extinction training. Rats then underwent tests for cue-induced reinstatement and general locomotor activity, prior to which they received an infusion of either saline (control) or baclofen/muscimol (B/M) to inactivate the PVT.

RESULTS

Relative to control animals of the same phenotype, GTs show a robust increase in cue-induced drug-seeking behavior following PVT inactivation, whereas the behavior of STs was not affected. PVT inactivation did not affect locomotor activity in either phenotype.

CONCLUSION

In GTs, the PVT appears to inhibit the expression of drug-seeking, presumably by attenuating the incentive value of the drug cue. Thus, inactivation of the PVT releases this inhibition in GTs, resulting in an increase in cue-induced drug-seeking behavior. PVT inactivation did not affect cue-induced drug-seeking behavior in STs, suggesting that the role of the PVT in encoding the incentive motivational value of drug cues differs between STs and GTs.

Sex differences in MDMA-induced toxicity in Sprague-Dawley rats

Recent evidence demonstrates that female subjects show exaggerated responses to 3,4-methylenedioxymethamphetamine (MDMA) compared with males. The aim of our study was to evaluate sex differences and the role of endogenous gonadal hormones on the effects of MDMA. Fifty-six intact and gonadectomized male and female Sprague-Dawley rats were randomly assigned to either MDMA (5 mg/kg) or saline treatment. Learning and memory were assessed using the Morris water maze (MWM). The expression of Bax and Bcl-2 in the hippocampus was detected by Western blotting. Behavioral analysis showed that MDMA led to memory impairment in both male and female rats. The female rats showed more sensitivity to impairment than the males, as assessed using all the memory parameters in the MWM. Ovariectomy attenuated the MDMA-induced memory impairment. By contrast, orchiectomized rats showed more impairment than MDMA-treated intact male rats. Bcl-2 and Bax were down-regulated and up-regulated in MDMA-treated male and female rats, respectively. MDMA treatment in the orchiectomized rats led to upregulation of Bax and down-regulation of Bcl-2. Ovariectomy attenuated the MDMA-induced up-regulation of Bax and caused more expression of Bcl-2 compared with what was observed in the MDMA-treated intact female rats. In summary, female rats showed exaggerated responses to the effects of MDMA and this may be explained by endogenous gonadal hormones.

The heat is on: Molecular mechanisms of drug-induced hyperthermia

Thermoregulation is an essential homeostatic process in which critical mechanisms of heat production and dissipation are controlled centrally in large part by the hypothalamus and peripherally by activation of the sympathetic nervous system. Drugs that disrupt the components of this highly orchestrated multi-organ process can lead to life-threatening hyperthermia. In most cases, hyperthermic agents raise body temperature by increasing the central and peripheral release of thermoregulatory neurotransmitters that ultimately lead to heat production in thermogenic effector organs skeletal muscle (SKM) and brown adipose tissue (BAT). In many cases hyperthermic drugs also decrease heat dissipation through peripheral changes in blood flow. Drug-induced heat production is driven by the stimulation of mechanisms that normally regulate the adaptive thermogenic responses including both shivering and non-shivering thermogenesis (NST) mechanisms. Modulation of the mitochondrial electrochemical proton/pH gradient by uncoupling protein 1 (UCP1) in BAT is the most well characterized mechanism of NST in response to cold, and may contribute to thermogenesis induced by sympathomimetic agents, but this is far from established. However, the UCP1 homologue, UCP3, and the ryanodine receptor (RYR1) are established mediators of toxicant-induced hyperthermia in SKM. Defining the molecular mechanisms that orchestrate drug-induced hyperthermia will be essential in developing treatment modalities for thermogenic illnesses. This review will briefly summarize mechanisms of thermoregulation and provide a survey of pharmacologic agents that can lead to hyperthermia. We will also provide an overview of the established and candidate molecular mechanisms that regulate the actual thermogenic processes in heat effector organs BAT and SKM.

A potential role for the paraventricular nucleus of the thalamus in mediating individual variation in Pavlovian conditioned responses

There is ample evidence to suggest that the paraventricular nucleus of the thalamus (PVT) mediates cue-reward learning, especially as it relates to drug-seeking behavior. However, its exact role in these complex processes remains unknown. Here we will present and discuss data from our own laboratory which suggests that the PVT plays a role in multiple forms of stimulus-reward learning, and does so via distinct neurobiological systems. Using an animal model that captures individual variation in response to reward-associated cues, we are able to parse the incentive from the predictive properties of reward cues and to elucidate the neural circuitry underlying these different forms of cue-reward learning. When rats are exposed to a classical Pavlovian conditioning paradigm, wherein a cue predicts food reward, some rats, termed sign-trackers, approach and manipulate the cue upon its presentation. This behavior is indicative of attributing incentive salience to the cue. That is, the cue gains excessive control over behavior for sign-trackers. In contrast, other rats, termed goal-trackers, treat the cue as a mere predictor, and upon its presentation go to the location of reward delivery. Based on our own data utilizing this model, we hypothesize that the PVT represents a common node, but differentially regulates the sign- vs. goal-tracking response. We postulate that the PVT regulates sign-tracking behavior, or the attribution of incentive salience, via subcortical, dopamine-dependent mechanisms. In contrast, we propose that goal-tracking behavior, or the attribution of predictive value, is the product of “top-down” glutamatergic processing between the prelimbic cortex (PrL) and the PVT. Together, data from our laboratory and others support a role for the PVT in cue-motivated behaviors and suggest that it may be an important locus within the neural circuitry that goes awry in addiction and related disorders.

Lesions of the fasciculus retroflexus alter footshock-induced cFos expression in the mesopontine rostromedial tegmental area of rats

Midbrain dopamine neurons are an essential part of the circuitry underlying motivation and reinforcement. They are activated by rewards or reward-predicting cues and inhibited by reward omission. The lateral habenula (lHb), an epithalamic structure that forms reciprocal connections with midbrain dopamine neurons, shows the opposite response being activated by reward omission or aversive stimuli and inhibited by reward-predicting cues. It has been hypothesized that habenular input to midbrain dopamine neurons is conveyed via a feedforward inhibitory pathway involving the GABAergic mesopontine rostromedial tegmental area. Here, we show that exposing rats to low-intensity footshock (four, 0.5 mA shocks over 20 min) induces cFos expression in the rostromedial tegmental area and that this effect is prevented by lesions of the fasciculus retroflexus, the principal output pathway of the habenula. cFos expression is also observed in the medial portion of the lateral habenula, an area that receives dense DA innervation via the fr and the paraventricular nucleus of the thalamus, a stress sensitive area that also receives dopaminergic input. High-intensity footshock (120, 0.8 mA shocks over 40 min) also elevates cFos expression in the rostromedial tegmental area, medial and lateral aspects of the lateral habenula and the paraventricular thalamus. In contrast to low-intensity footshock, increases in cFos expression within the rostromedial tegmental area are not altered by fr lesions suggesting a role for non-habenular inputs during exposure to highly aversive stimuli. These data confirm the involvement of the lateral habenula in modulating the activity of rostromedial tegmental area neurons in response to mild aversive stimuli and suggest that dopamine input may contribute to footshock- induced activation of cFos expression in the lateral habenula.

Mephedrone (4-methylmethcathinone, 'meow'): acute behavioural effects and distribution of Fos expression in adolescent rats

Mephedrone (4-methylmethcathinone) is a novel recreational drug that has rapidly increased in popularity in recent years. Users report mephedrone as having the stimulant-like qualities of methamphetamine and cocaine, combined with the prosocial, entactogenic effects of 3,4-methylenedioxymethamphetamine (MDMA). Anecdotal and case study reports indicate that mephedrone may have the potential to engender compulsive patterns of use as well as toxicity in overdose. However, there have been almost no neuropharmacological investigations of the drug up to this point. Here we examined the effects of two different mephedrone doses [15 and 30 mg/kg, intraperitoneal (IP)] relative to the well-known stimulant methamphetamine (2 mg/kg IP) in adolescent rats. Rats were injected, assessed for locomotor activity for 60 minutes and then tested in a 10-minute social preference test (measuring time spent in close proximity to a real rat versus a dummy rat). Their brains were then processed using Fos immunohistochemistry to determine patterns of brain activation. Results showed that mephedrone caused profound locomotor hyperactivity at both dose levels while tending to reduce social preference. Patterns of Fos expression with mephedrone resembled a combination of those observed with methamphetamine and MDMA, with particularly strong Fos expression in the cortex, dorsal and ventral striatum, ventral tegmental area (typical of both MDMA and methamphetamine) and supraoptic nucleus (typical of MDMA). These results demonstrate for the first time the powerful stimulant effects of mephedrone in animal models and its capacity to activate mesolimbic regions. These results also provide some empirical basis to user reports that mephedrone subjectively resembles a MDMA/methamphetamine hybrid.

Active and passive MDMA ('ecstasy') intake induces differential transcriptional changes in the mouse brain

3,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') is a recreational drug widely used by adolescents and young adults. Although its rewarding effects are well established, there is controversy on its addictive potential. We aimed to compare the consequences of active and passive MDMA administration on gene expression in the mouse brain since all previous studies were based on passive MDMA administration. We used a yoked-control operant intravenous self-administration paradigm combined with microarray technology. Transcriptomic profiles of ventral striatum, frontal cortex, dorsal raphe nucleus and hippocampus were analysed in mice divided in contingent MDMA, yoked MDMA and yoked saline groups, and several changes were validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The comparison of contingent MDMA and yoked MDMA vs. yoked saline mice allowed the identification of differential expression in several genes, most of them with immunological and inflammatory functions, but others being involved in neuroadaptation. In the comparison of contingent MDMA vs. yoked MDMA administration, hippocampus and the dorsal raphe nucleus showed statistically significant changes. The altered expression of several genes involved in neuroadaptative changes and synapse function, which may be related to learning self-administration behaviour, could be validated in these two brain structures. In conclusion, our study shows a strong effect of MDMA administration on the expression of immunological and inflammatory genes in all the four brain regions studied. In addition, experiments on MDMA self-administration suggest that the dorsal raphe nucleus and hippocampus may be involved in active MDMA-seeking behaviour, and show specific alterations on gene expression that support the addictive potential of this drug.

Brain pattern of histone H3 phosphorylation after acute amphetamine administration: its relationship to brain c-fos induction is strongly dependent on the particular brain area

Recent evidence strongly suggests a critical role of chromatin remodelling in the acute and chronic effects of addictive drugs. We reasoned that Immunohistochemical detection of certain histone modifications may be a more specific tool than induction of immediate early genes (i.e. c-fos) to detect brain areas and neurons that are critical for the action of addictive drugs. Thus, in the present work we studied in adult male rats the effects of a high dose of amphetamine on brain pattern of histone H3 phosphorylation in serine 10 (pH3S(10)) and c-fos expression. We firstly observed that amphetamine-induced an increase in the number of pH3S(10) positive neurons in a restricted number of brain areas, with maximum levels at 30 min after the drug administration that declined at 90 min in most areas. In a second experiment we studied colocalization of pH3S(10) immunoreactivity (pH3S(10)-IR) and c-fos expression. Amphetamine increased c-fos expression in medial prefrontal cortex (mPFC), dorsal striatum, nucleus accumbens (Acb), major Island of Calleja (ICjM), central amygdala (CeA), bed nucleus of stria terminalis lateral dorsal (BSTld) and paraventricular nucleus of the hypothalamus (PVN). Whereas no evidence for increase in pH3S(10) positive neurons was found in the mPFC and the PVN, in the striatum and the Acb basically all pH3S(10) positive neurons showed colocalization with c-fos. In ICjM, CeA and BSTld a notable degree of colocalization was found, but an important number of neurons expressing c-fos were negative for pH3S(10). The present results give support to the hypothesis that amphetamine-induced pH3S(10)-IR showed a more restricted pattern than brain c-fos induction, being this difference strongly dependent on the particular brain area studied. It is likely that those nuclei and neurons showing pH3S(10)-IR are more specifically associated to important effects of the drug, including neural plasticity. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.

MDMA-induced c-Fos expression in oxytocin-containing neurons is blocked by pretreatment with the 5-HT-1A receptor antagonist WAY 100635

The popular party drug MDMA (3,4-methylenedioxymethamphetamine, "Ecstasy") increases sociability in both humans and laboratory animals. Recent research suggests that these prosocial effects may involve serotonin (5-HT)-stimulated hypothalamic release of the neuropeptide oxytocin. WAY 100635, a 5-HT(1A) receptor antagonist, prevents MDMA-induced increases in plasma oxytocin and also reduces MDMA-mediated increases in social interaction in rats. The present study used c-Fos immunohistochemistry to determine the possible role of 5-HT(1A) receptors in MDMA-mediated activation of oxytocin synthesizing neurons. Male Wistar rats (n=8/group) were administered MDMA (10 mg/kg, i.p.) with or without WAY 100635 (1 mg/kg, i.p.) pre-treatment and c-Fos expression was then assessed throughout the brain. MDMA significantly increased locomotor activity and this effect was partly prevented by WAY 100635, in agreement with previous studies. WAY 100635 significantly reduced MDMA-induced c-Fos expression in a subset of brain regions examined. A particularly prominent reduction was seen in the oxytocin-positive neurons of the supraoptic nucleus and paraventricular hypothalamus, with more modest reductions in the Islands of Calleja, median preoptic nucleus, somatosensory cortex and nucleus of the solitary tract. WAY 100635 did not alter MDMA-induced c-Fos expression in the striatum, thalamus, or central amygdala. These results indicate that MDMA's action on oxytocin producing cells in the hypothalamus is mediated through 5-HT(1A) receptors and that certain specific cortical, limbic and brainstem sites are also activated by MDMA via these receptors.

Behavioral effects of MDMA ('ecstasy') on adult zebrafish

3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') is a potent psychedelic drug inducing euphoria and hypersociability in humans, as well as hyperactivity and anxiety in rodents. Adult zebrafish (Danio rerio) have become a widely used species in neurobehavioral research. Here, we explore the effects of a wide range (0.25-120 mg/l) of acute MDMA doses on zebrafish behavior in the novel tank test. Although MDMA was inactive at lower doses (0.25-10 mg/l), higher doses reduced bottom swimming and immobility (40-120 mg/l) and impaired intrasession habituation (10-120 mg/l). MDMA also elevated brain c-fos expression, collectively confirming the usage of zebrafish models for screening of hallucinogenic compounds.

Behavioral sensitization and cross-sensitization between methylphenidate amphetamine, and 3,4-methylenedioxymethamphetamine (MDMA) in female SD rats

The psychostimulants amphetamine and methylphenidate (MPD/Ritalin) are the drugs most often used to treat attention deficit hyperactivity disorder (ADHD). In addition, students of all ages take these drugs to improve academic performance but also abuse them for pleasurable enhancement. In addition, other psychostimulants such as 3,4-methylenedioxymethamphetamine (MDMA/ecstasy) are used/abused for similar objectives. One of the experimental markers for the potential of a drug to produce dependence is its ability to induce behavioral sensitization and cross sensitization with other drugs of abuse. The objective of this study is to use identical experimental protocols and behavioral assays to compare in female rats the effects of amphetamine, MPD and MDMA on locomotor activity and to determine if they induce behavioral sensitization and/or cross sensitization with each other. The main findings of this study are as follows: (1) acute amphetamine, MPD and MDMA all elicited increases in locomotor activity; (2) chronic administration of an intermediate dose of amphetamine or MPD elicited behavioral sensitization; (3) chronic administration of MDMA elicited behavioral sensitization in some animals and behavioral tolerance in others; (4) cross sensitization between MPD and amphetamine was observed; and (5) MDMA did not show either cross sensitization or cross tolerance with amphetamine. In conclusion, these results suggest that MDMA acts by different mechanisms compared to MPD and amphetamine.

Pharmacological recruitment of the GABAergic tail of the ventral tegmental area by acute drug exposure

BACKGROUND AND PURPOSE

The tail of the ventral tegmental area (tVTA), also called the rostromedial tegmental nucleus, is a newly defined brain structure and a potential control centre for dopaminergic activity. It was identified by the induction of DeltaFosB following chronic cocaine exposure. In this work, we screened 20 drugs for their ability to induce FosB/DeltaFosB in the tVTA.

EXPERIMENTAL APPROACH

Immunohistochemistry following systemic drug administration was used to study FosB/DeltaFosB induction in the tVTA of adult rats. Double-staining was used to determine whether dopamine or GABA neurones are involved in this induction.

KEY RESULTS

The acute injection of the psychostimulant drugs cocaine, D-amphetamine, (+/-)-3,4-methylenedioxymethamphetamine (MDMA), methylphenidate or caffeine, induced the expression of FosB/DeltaFosB in the tVTA GABAergic cells. No induction was observed following exposure to ethanol, diazepam, γ-hydroxybutyric acid (GHB), morphine, ketamine, phencyclidine (PCP), Δ(9)-tetrahydrocannabinol (THC), sodium valproic acid or gabapentin. To evaluate the role of monoamine transporters in the psychostimulant-induced expression of FosB/DeltaFosB, we tested the antidepressant drugs reboxetine, nortriptyline, fluoxetine and venlafaxine (which target the noradrenaline and/or the 5-hydroxytryptamine transporters), the 5-hydroxytryptamine releasing agent dexfenfluramine, and the dopamine transporter inhibitor GBR12909. Only GBR12909 was able to induce FosB/DeltaFosB expression in the tVTA, showing that this induction is mediated by dopamine.

CONCLUSIONS AND IMPLICATIONS

Newly described brain structures may help to increase our knowledge of brain function, pathology and targets for treatments. FosB/DeltaFosB induction in the tVTA is a common feature of drugs sharing psychostimulant properties but not of drugs sharing risk of abuse.

Ascorbic acid and α-tocopherol supplement starting prenatally enhances the resistance of nucleus tractus solitarius neurons to hypobaric hypoxic challenge

Hypobaric hypoxia, encountered at high altitude, could result in severe consequences. Ascorbic acid (AA) and α-tocopherol (αTC), the two readily available over-the-counter antioxidants, are known to protect nervous tissue against oxidative stress. Here we study whether AA or αTC supplement starting prenatally protects animals against hypobaric hypoxic challenge at adulthood. Expressions of c-fos and the NR1 subunit of the N-methyl-D-aspartate receptors in the nucleus tractus solitarius (NTS) subserving cardiorespiratory functions were investigated. AA and αTC supplement reduced the number of c-fos immunoreactive neurons and intensity of NR1 expression in young and adult animals under normoxia. The treatment, in addition, attenuated the activation of NTS neurons, in terms of c-fos and NR1 expressions, and reduced the anxiety behaviors of adult rats subjected to hypobaric hypoxic challenge. Reduction of c-fos immunoreactive neurons was found concentrated in the chemoreceptor, baroreceptor, and tracheobronchial tree NTS subnuclei that receive corresponding afferents. The protective effect was not found in normal adult animals supplemented with AA or αTC a week before hypobaric hypoxic challenge. In short, prenatal and sustained AA or αTC supplement altered NTS substrate and ameliorated animals' reactions to hypobaric hypoxic insult, suggesting that this may be considered to protect animals from hypoxic insults from young to adult.

fMRI study of brain activity elicited by oral parafunctional movements

Parafunctional masticatory activity, such as the tooth clenching and grinding that is associated with bruxism, is encountered by clinicians in many disciplines, including dentistry, neurology and psychiatry. Despite this, little is known about the neurological basis for these activities. To identify the brain network engaged in such complex oromotor activity, functional magnetic resonance imaging (fMRI) was used to elucidate the brain activation patterns of 20 individuals (10 males and 10 females, mean s.d. age of 26.3+/-4.1 years) with (parafunctional, PFx group, 5M/5F) and without (normal functional, NFx group, 5 M/5F) self-reported parafunctional grinding and clenching habits during clenching and grinding tasks. Subject group classification was based on: (i) self-reported history, (ii) clinical examination, (iii) evaluation of dental casts and (iv) positive responses to the temporomandibular disorder (TMD) History Questionnaire [Dworkinand LeResche, Journal of Craniomandibular Disorders, (1992) 6:301]. While subjects performed these oromotor tasks, each wore a custom-designed oral appliance minimizing head motion during imaging. Mean per cent signal changes showed significant between group differences in motor cortical (supplementary motor area, sensorimotor cortex and rolandic operculum) and subcortical (caudate) regions. Supplementary motor area data suggest that motor planning and initiation, particularly during the act of clenching, are less prominent in individuals with oromotor parafunctional behaviours. The overall extent of activated areas was reduced in subjects with self-reported parafunctional masticatory activity compared with the controls. This study's methodology and findings provide an initial step in understanding the neurological basis of parafunctional masticatory activities that are relevant for therapeutic research applications of temporomandibular joint and muscle disorders and associated comorbidities.

Metabolism of [14C]-5-chloro-1,3-benzodioxol-4-amine in male Wistar-derived rats following intraperitoneal administration

[14C]-5-chloro-1,3-benzodioxol-4-amine was administered intraperitoneally (i.p.) to bile duct-cannulated rats (Alpk:ApfSD, Wistar derived) at 25 mg kg-1 to determine the rates and routes of excretion of the compound and to investigate its metabolic fate. A total of 89.1% of the dose was excreted in the 48 h following administration, the majority being recovered in the urine during the first 12 h. The main metabolite in both urine and bile, detected by high-performance liquid chromatography (HPLC) with radioprofiling and mass spectrometry, was identified as a demethylenated monosulfate conjugate. Unchanged parent compound formed a major component of the radiolabel excreted in urine and, in addition to unchanged parent and demethylenated sulphate conjugate, a large number of minor metabolites were detected in urine and bile. The overall metabolic fate of 5-chloro-1,3-benzodioxol-4-amine in the rat was complex, with some similarities to previously studied methylenedioxyphenyl compounds.

CB1 cannabinoid receptor modulates 3,4-methylenedioxymethamphetamine acute responses and reinforcement

BACKGROUND

3,4-Methylenedioxymethamphetamine (MDMA) is a popular recreational drug widely abused by young people. The endocannabinoid system is involved in the addictive processes induced by different drugs of abuse. However, the role of this system in the pharmacological effects of MDMA has not yet been clarified.

METHODS

Locomotion, body temperature, and anxiogenic-like responses were evaluated after acute MDMA administration in CB(1) cannabinoid receptor 1 knockout mice. Additionally, MDMA rewarding properties were investigated in the place conditioning and the intravenous self-administration paradigms. Extracellular levels of dopamine (DA) in the nucleus accumbens were also analyzed after a single administration of MDMA by in vivo microdialysis.

RESULTS

Acute MDMA administration increased locomotor activity, body temperature, and anxiogenic-like responses in wild-type mice, but these responses were lower or abolished in knockout animals. 3,4-Methylenedioxymethamphetamine produced similar conditioned place preference and increased dopamine extracellular levels in the nucleus accumbens in both genotypes. Nevertheless, CB(1) knockout mice failed to self-administer MDMA at any of the doses used.

CONCLUSIONS

These results indicate that CB(1) cannabinoid receptors play an important role in the acute prototypical effects of MDMA and are essential in the acquisition of an operant behavior to self-administer this drug.

Neural correlates of MDMA ("Ecstasy")-induced social interaction in rats

The popular drug 3,4 methylenedioxymethamphetamine (MDMA, "Ecstasy", "the Love Drug") produces feelings of love and closeness in humans and induces analogous prosocial and antiaggressive effects in laboratory animals. Here we examined the specific brain regions that may be involved in these prosocial effects. Male Wistar rats were pretreated with a moderate dose of MDMA (5 mg/kg) or vehicle and then either kept alone in a familiar test chamber for 60 min (groups MDMA-ALONE and VEHICLE-ALONE) or allowed to engage in social interaction in the familiar test chamber with an unfamiliar same-sex conspecific for 60 min (groups MDMA-SOCIAL and VEHICLE-SOCIAL). Rats in the MDMA-SOCIAL group showed much greater overall social interaction than rats in the VEHICLE-SOCIAL group, with microanalysis revealing increased general investigation of other rats but decreased anogenital sniffing. Analysis of neural activation across 39 brain regions using Fos immunohistochemistry showed the following results: (1) VEHICLE-SOCIAL and VEHICLE-ALONE groups did not differ in Fos expression, indicating that a social context per se did not affect Fos expression, (2) MDMA-treated groups showed significantly increased Fos expression relative to VEHICLE treated groups in 30 brain regions, (3) the MDMA-SOCIAL group showed augmented Fos expression relative to the MDMA-ALONE group in six brain regions including the caudate-putamen (medial), medial preoptic area, paraventricular thalamic nucleus, central amygdala, ventromedial hypothalamic nucleus, and the medial amygdala (posterodorsal), and (4) the MDMA-SOCIAL group (but not the MDMA-ALONE group) showed augmented Fos expression relative to the VEHICLE groups in the nucleus accumbens, ventral tegmental area and periaqueductal grey. These results indicate that a moderate dose of MDMA given in a social context causes considerably greater brain activation than the same dose given to solitary rats. This activation involves specific neural circuits that are known to regulate affiliative behavior, perhaps by modulating the incentive value of social stimuli. A possible role for the neuropeptide oxytocin in mediating the prosocial effects of MDMA is discussed.

Changes in leptin, ghrelin, growth hormone and neuropeptide-Y after an acute model of MDMA and methamphetamine exposure in rats

Club drug abuse is a growing problem in the United States. Beyond addiction and toxicity are endocrine effects which are not well characterized. Specifically, the changes in appetite following exposure to drugs of abuse are an interesting but poorly understood phenomenon. Serum hormones such as leptin, ghrelin, growth hormone (GH), and neuropeptide-Y (NP-Y) are known to affect appetite, but have not been studied extensively with drugs of abuse. In this work, we examine the effects of club drugs 3,4-methylenedioxymethamphetamine (MDMA) (ecstasy) and methamphetamine (METH) (doses of 5, 20 and 40 mg/kg) on serum concentrations of these hormones in adult male Sprague-Dawley rats 6, 12, 24 and 48 hours after drug administration. In a dose-dependent manner, MDMA was shown to cause transient significant decreases in serum leptin and GH followed by a base line recovery after 24 hours. Conversely, serum ghrelin increased and normalized after 24 hours. Interestingly, serum NP-Y showed a steady decrease in both treatment of MDMA and METH at different time points and dosages. In humans, abuse of these drugs reduces eating. As evident from these data, acute administration of METH and MDMA had significant effects on different serum hormone levels involved in appetite regulation. Future studies should be performed to see how chronic, low dose drug administration would affect hormone levels and try to answer questions about the physiological mechanisms involved in the anorexic paradigm observed in drug use.

Functional internal complexity of amygdala: focus on gene activity mapping after behavioral training and drugs of abuse

The amygdala is a heterogeneous brain structure implicated in processing of emotions and storing the emotional aspects of memories. Gene activity markers such as c-Fos have been shown to reflect both neuronal activation and neuronal plasticity. Herein, we analyze the expression patterns of gene activity markers in the amygdala in response to either behavioral training or treatment with drugs of abuse and then we confront the results with data on other approaches to internal complexity of the amygdala. c-Fos has been the most often studied in the amygdala, showing specific expression patterns in response to various treatments, most probably reflecting functional specializations among amygdala subdivisions. In the basolateral amygdala, c-Fos expression appears to be consistent with the proposed role of this nucleus in a plasticity of the current stimulus-value associations. Within the medial part of the central amygdala, c-Fos correlates with acquisition of alimentary/gustatory behaviors. On the other hand, in the lateral subdivision of the central amygdala, c-Fos expression relates to attention and vigilance. In the medial amygdala, c-Fos appears to be evoked by emotional novelty of the experimental situation. The data on the other major subdivisions of the amygdala are scarce. In conclusion, the studies on the gene activity markers, confronted with other approaches involving neuroanatomy, physiology, and the lesion method, have revealed novel aspects of the amygdala, especially pointing to functional heterogeneity of this brain region that does not fit very well into contemporarily active debate on serial versus parallel information processing within the amygdala.

Ethanol-MDMA interactions in rats: the importance of interval between repeated treatments in biobehavioral tolerance and sensitization to the combination

RATIONALE

In our previous work, we showed that ethanol (EtOH) potentiates 3,4-methylenedioxymethamphetamine (MDMA)-induced hyperlocomotion while protecting against its hyperthermic effects. Whereas the effect on activity were found on all days (although declining over the three first days), the protection against hyperthermia completely disappeared on the second day. The latter effect was previously thought to reflect tolerance to ethanol or the combination, per se.

OBJECTIVE

In the present study, we changed the treatment regimen to irregular and longer intervals between treatments (48, 120, and again 48 h) to check if tolerance was still observed.

RESULTS

We found progressive sensitization of locomotor activity to EtOH (1.5 g/kg, i.p.)+MDMA (6.6 mg/kg, i.p.), and a partial EtOH protection against MDMA-induced hyperthermia that persisted after the first drug challenge day. When the monoamine neurotransmitters, dopamine, and serotonin were assessed 2 weeks after treatment, we found no consistent effect on the concentration of any of these neurotransmitters, whatever the treatment. Similarly, we found that regional brain concentrations of MDMA were not significantly affected by EtOH at a 45-min post-treatment delay; however, the overall ratio of the metabolite 3,4-methylenedioxyamphetamine (MDA) to MDMA was lower (overall, -16%) in animals treated with the combination compared to MDMA alone, indicating possible contribution of pharmacokinetic factors. This difference was especially marked in the striatum (-25%).

CONCLUSIONS

These findings shed new light on the consequences of EtOH-MDMA, taken together at a nearly normal ambient temperature, both in terms of motivation and potential risks for recreational drug users.

A role for oxytocin and 5-HT(1A) receptors in the prosocial effects of 3,4 methylenedioxymethamphetamine ("ecstasy")

The drug 3,4 methylenedioxymethamphetamine (MDMA; ecstasy) has a widely documented ability to increase feelings of love and closeness toward others. The present study investigated whether oxytocin, a neuropeptide involved in affiliative behavior, may play a role in this effect. A moderate (5 mg/kg, i.p.) dose of MDMA increased social interaction in male Wistar rats, primarily by increasing the amount of time rats spent lying adjacent to each other. MDMA (5 mg/kg) activated oxytocin-containing neurons in the supraoptic and paraventricular nuclei of the hypothalamus, as shown by Fos immunohistochemistry. MDMA (5 mg/kg i.p.) also increased plasma oxytocin levels and this effect was prevented by pre-treatment with the 5-HT(1A) antagonist N-[2-[4-(2-methyoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide maleate salt (WAY 100,635; 1 mg/kg i.p.). The oxytocin receptor antagonist tocinoic acid (20 microg, i.c.v.) had no effect on social behavior when given alone but significantly attenuated the facilitation of social interaction produced by MDMA (5 mg/kg). The 5-HT(1A) agonist 8-hydroxy-2-(di-n-propylamino)-tetraline) (8-OH-DPAT, 0.25 mg/kg, i.p.) increased social behavior in a similar way to MDMA and this effect was also significantly attenuated by tocinoic acid. Taken together, these results suggest that oxytocin release, stimulated by MDMA through 5-HT(1A) receptors, may play a key role in the prosocial effects of MDMA and underlie some of the reinforcing effects of the drug.

High ambient temperature increases 3,4-methylenedioxymethamphetamine (MDMA, “ecstasy”)-induced Fos expression in a region-specific manner

3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy") is a popular drug that is often taken under hot conditions at dance clubs. High ambient temperature increases MDMA-induced hyperthermia and recent studies suggest that high temperatures may also enhance the rewarding and prosocial effects of MDMA in rats. The present study investigated whether ambient temperature influences MDMA-induced expression of Fos, a marker of neural activation. Male Wistar rats received either MDMA (10 mg/kg i.p.) or saline, and were placed in test chambers for 2 h at either 19 or 30 degrees C. MDMA caused significant hyperthermia at 30 degrees C and a modest hypothermia at 19 degrees C. The 30 degrees C ambient temperature had little effect on Fos expression in vehicle-treated rats. However MDMA-induced Fos expression was augmented in 15 of 30 brain regions at the high temperature. These regions included (1) sites associated with thermoregulation such as the median preoptic nucleus, dorsomedial hypothalamus and raphe pallidus, (2) the supraoptic nucleus, a region important for osmoregulation and a key mediator of oxytocin and vasopressin release, (3) the medial and central nuclei of the amygdala, important in the regulation of social and emotional behaviors, and (4) the shell of the nucleus accumbens and (anterior) ventral tegmental area, regions associated with the reinforcing effects of MDMA. MDMA-induced Fos expression was unaffected by ambient temperature at many other sites, and was diminished at high temperature at one site (the islands of Calleja), suggesting that the effect of temperature on MDMA-induced Fos expression was not a general pharmacokinetic effect. Overall, these results indicate that high temperatures accentuate key neural effects of MDMA and this may help explain the widespread use of the drug under hot conditions at dance parties as well as the more hazardous nature of MDMA taken under such conditions.

Rewarding effects of 3,4-methylenedioxymethamphetamine ("Ecstasy") in dominant and subordinate OF-1 mice in the place preference conditioning paradigm

We tested the ability of 3,4-methylenedioxymethamphetamine (MDMA) to induce conditioned place preference (CPP) in dominant and subordinate OF-1 mice subjected to cohabitation and repeated sessions of agonistic confrontation, as well as in non-confronted mice. We selected doses of MDMA (2, 6, 10 mg/kg) previously reported to induce CPP in mice and we measured expression of c-Fos evoked by the treatments in non-confronted mice. MDMA induced c-Fos protein in several corticolimbic regions involved in drug-induced reward. Mice were exposed to brief sessions of agonistic confrontation on 5 consecutive days. Determinations of circulating hormones and drug conditioning tests were carried out on completion of the encounters. The results of hormone assays indicated that dominant mice had higher serum concentrations of testosterone, but lower levels of corticosterone, than submissive mice. Post-conditioning tests after drug conditioning (4 injections of MDMA or saline on alternate days) showed that MDMA significantly produced CPP at doses of 2 and 6 mg/kg, but not at 10 mg/kg, an inverted U-shaped pattern of conditioning that was invariable in non-confronted, dominant and subordinate mice. These results demonstrate that the endocrine and behavioural correlates linked to social status and social stress in mice are not paralleled by significant changes in the rewarding efficacy of MDMA in the CPP paradigm under the specific conditions tested.

Ecstasy Toxicity

Ecstasy use is a growing problem in the United States. Techniques to demonstrate and characterize the toxicity associated with its use have been limited and employed infrequently. In this study, we compare the deleterious effects of ecstasy use in rats with that of methamphetamine and traumatic brain injury. Specifically, we investigate the degradation of structural proteins alphaII-spectrin and tau by the pro-necrotic calpain and pro-apoptotic caspase systems. Ecstasy-induced neurotoxicity is shown after 24 hours, although to a much lesser extent than that of methamphetamine or traumatic brain injury. Neurotoxicity is still evident after 72 hours. Furthermore, apoptosis of the liver is seen 72 hours after ecstasy use. Use of protease inhibitors may be useful in preventing ecstasy-induced toxicity.

Hyperthermic Syndromes Induced by Toxins

Normal thermogenesis requires a complex interaction between systems that generate and dissipate heat. Serving as director of thermogenesis, the hypothalamus activates the sympathetic nervous system along with the thyroid and adrenal glands to respond to changes in body temperature. Working in concert, these systems result in heat generation by uncoupling of oxidative phosphorylation, combined with impaired heat dissipation through vasoconstriction. In this article, the authors discuss serotonin and sympathomimetic syndromes, neuroleptic malignant syndrome,and malignant hyperthermia and how these syndromes affect the hypothalamic and sympathetic nervous systems, resulting at times in severe hyperthermia. Current treatment recommendations and future trends in treatment are also discussed.

Chronic treatment with a serotonin(2) receptor (5-HT(2)R) agonist modulates the behavioral and cellular response to (+)-3,4-methylenedioxymethamphetamine [(+)-MDMA]

3,4-Methylenedioxymethamphetamine [MDMA; ecstasy] evokes a multifaceted subjective experience in human users which includes stimulation, feelings of well-being, mood elevation, empathy towards others as well as distortions in time, sensation and perception. Aspects of this unique psychopharmacology of MDMA are thought to be related to its potent actions to release serotonin (5-HT) and indirectly stimulate the 5-HT(2A) receptor (5-HT(2A)R). In the present studies, we examined the interrelationship between down-regulation of 5-HT(2A)R expression and the behaviorally stimulatory effects generated by acute administration of (+)-MDMA, the most potent enantiomer of (+/-)-MDMA. Male Sprague-Dawley rats were chronically treated with the preferential 5-HT(2A)R agonist 2,5-dimethoxy-4-iodoamphetamine (DOI) which has been shown to down-regulate expression of the 5-HT(2A)R, but not the closely related 5-HT(2C)R. While chronic DOI treatment did not alter the functional sensitivity of either the 5-HT(2A)R or 5-HT(2C)R, this regimen enhanced (+)-MDMA-evoked hyperactivity. Subsequent analysis of c-Fos and 5-HT(2A)R immunoreactivity in brain sections demonstrated that DOI treatment decreased the number of (+)-MDMA-induced c-Fos immunopositive nuclei and 5-HT(2A)R immunostaining in select cortical and striatal areas. These results indicate that chronic DOI exposure results in an enhanced behavioral response to (+)-MDMA and in a pattern of neuronal activation which resembles that seen in psychostimulant sensitization. These data also suggest that expression of the 5-HT(2A)R in the NAc and PFC may play a role in the sensitivity to the locomotor-stimulating effects of (+)-MDMA and in the processes of neural regulation upon repeated psychostimulant administration.

Analysis of transcriptional responses in the mouse dorsal striatum following acute 3,4-methylenedioxymethamphetamine (ecstasy): identification of extracellular signal-regulated kinase-controlled genes

3,4-Methylenedioxymethamphetamine (ecstasy), a widely used recreational drug with psychoactive properties, induces both serotonin and dopamine release in the brain. However, little is known about its intracellular effects. We previously showed that 3,4-methylenedioxymethamphetamine rewarding effects in mice were dependent upon extracellular signal-regulated kinase activation and that dorsal striatum was a critical region for mediating extracellular signal-regulated kinase-dependent Egr1 3,4-methylenedioxymethamphetamine-induced transcription. Here, we extend these findings by showing that 3,4-methylenedioxymethamphetamine is indeed able to activate extracellular signal-regulated kinase within this structure. To identify genes regulated by acute 3,4-methylenedioxymethamphetamine in the mice dorsal striatum, and selectively controlled by this kinase, we performed microarray experiments by using a selective inhibitor of extracellular signal-regulated kinase activation, SL327. Of the approximately 24,000 genes from the microarray, 27 showed altered expression after exposure to 3,4-methylenedioxymethamphetamine, and among these, 59% were partially or totally inhibited by SL327 pretreatment. Our results showed that the genes regulated by 3,4-methylenedioxymethamphetamine encode proteins that belong to transcription factors family, signaling pathways (phosphatases, cytoskeleton regulation), and synaptic functions. These early changes, and especially those controlled by extracellular signal-regulated kinase activation might play significant roles in the expression of many of the behaviors that occur following 3,4-methylenedioxymethamphetamine taking.

Expression of c-Fos in the mouse Edinger-Westphal nucleus following ethanol administration is not secondary to hypothermia or stress

Restraint stress, lipopolysaccharide (LPS), and ethanol (EtOH) administration have all been found to induce c-Fos in the brain, and to cause hypothermia. The present study was designed to assess whether the c-Fos expression that occurs in the Edinger-Westphal nucleus (EW) after EtOH administration is independent of the hypothermia or any stress effects that occur. To test this, we used restraint stress and LPS in addition to EtOH, and also examined two control areas, the dorsal raphe nucleus (DRN) and the periaqueductal gray (PAG), in addition to EW. Male C57BL6/J mice were used. Groups of mice received intraperitoneal (IP) injections of EtOH (2 g/kg), LPS (600 microg/kg or 50 microg/kg), or saline. A separate group of mice received no injection, but were placed in plastic restrainers for the entirety of the experiment. For all groups, core temperatures were monitored rectally every 30 min for 3 h postinjection, after which, the animals were sacrificed. Then, the number of Fos-positive cells in the brain regions of the EW, DRN, and PAG was quantified. Both EtOH and restraint stress induced a transient hypothermia, where core temperature (Tc) declined immediately and then rose again. Both doses of LPS induced a slower developing, longer lasting hypothermia, while saline had no effect on Tc. Only EtOH induced a significant amount of c-Fos in EW, while both doses of LPS and restraint stress induced c-Fos in DRN, and only restraint stress caused induction in PAG. These data demonstrate that activation of EW after EtOH is unrelated to hypothermia or stress.

Toxin-induced hyperthermic syndromes

Toxin-induced hyperthermic syndromes are important to consider in the differential diagnosis of patients presenting with fever and muscle rigidity. If untreated, toxin-induced hyperthermia may result in fatal hyperthermia with multisystem organ failure. All of these syndromes have at their center the disruption of normal thermogenic mechanisms, resulting in the activation of the hypothalamus and sympathetic nervous systems.The result of this thermogenic dysregulation is excess heat generation combined with impaired heat dissipation. Although many similarities exist among the clinical presentations and pathophysiologies of toxin-induced hyperthermic syndromes, important differences exist among their triggers and treatments. Serotonin syndrome typically occurs within hours of the addition ofa new serotonergic agent or the abuse of stimulants such as MDMA or methamphetamine. Treatment involves discontinuing the offending agent and administering either a central serotonergic antagonist, such as cyproheptadine or chlorpromazine, a benzodiazepine, or a combination of the two. NMS typically occurs over hours to days in a patient taking a neuroleptic agent; its recommended treatment is generally the combination of a central dopamine agonist, bromocriptine or L-dopa, and dantrolene. In those patients in whom it is difficult to differentiate between serotonin and neuroleptic malignant syndromes, the physical examination may be helpful:clonus and hyperreflexia are more suggestive of serotonin syndrome,whereas lead-pipe rigidity is suggestive of NMS. In patients in whom serotonin syndrome and NMS cannot be differentiated, benzodiazepines represent the safest therapeutic option. MH presents rapidly with jaw rigidity, hyperthermia, and hypercarbia. Although it almost always occurs in the setting of surgical anesthesia, cases have occurred in susceptible individuals during exertion. The treatment of MH involves the use of dantrolene. Future improvements in understanding the pathophysiology and clinical presentations of these syndromes will undoubtedly result in earlier recognition and better treatment strategies.

Serotonin (1A) receptor involvement in acute 3,4-methylenedioxymethamphetamine (MDMA) facilitation of social interaction in the rat

The current study assessed whether various co-administered serotonin (5-HT) receptor antagonists could prevent some of the acute behavioral effects of 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") in rats. In the social interaction test, MDMA (5 mg/kg) significantly increased the duration of total social interaction between two conspecifics meeting for the first time. Microanalysis showed that MDMA increased adjacent lying and approach behaviours while reducing anogenital sniffing. MDMA (5 mg/kg) also caused elements of the serotonin syndrome including low body posture and piloerection. In the emergence test, MDMA significantly increased hide time and emergence latency indicating increased anxiety-like behavior. Pretreatment with the 5HT 1A receptor antagonist, WAY 100635 (1 mg/kg), prevented MDMA-induced increases in social interaction and markers of the serotonin syndrome while the 5-HT 1B receptor antagonist GR 55562 (1 mg/kg) and 5-HT 2A receptor antagonist ketanserin (1 mg/kg) were ineffective. The 5-HT 2B/2C receptor antagonist, SB 206553 (2 mg/kg), prevented MDMA-induced prosocial effects but caused pronounced thigmotaxis (hyperactivity at the periphery of the testing chamber). The anxiogenic effect of MDMA on the emergence test was not prevented by pretreatment with any of the 5-HT receptor antagonists tested. These results indicate that prosocial effect of MDMA may involve 5-HT 1A and possibly 5-HT 2B/2C receptors. In contrast, MDMA-induced generalised anxiety, as measured by the emergence test, seems unlikely to involve the 5-HT 1A, 5-HT 1B or 5-HT 2A, 5-HT 2B or 5-HT 2C receptors.

A comparative study on the acute and long-term effects of MDMA and 3,4-dihydroxymethamphetamine (HHMA) on brain monoamine levels after i.p. or striatal administration in mice

1. This study investigated whether the immediate and long-term effects of 3,4-methylenedioxymethamphetamine (MDMA) on monoamines in mouse brain are due to the parent compound and the possible contribution of a major reactive metabolite, 3,4-dihydroxymethamphetamine (HHMA), to these changes. The acute effect of each compound on rectal temperature was also determined. 2. MDMA given i.p. (30 mg kg(-1), three times at 3-h intervals), but not into the striatum (1, 10 and 100 microg, three times at 3-h intervals), produced a reduction in striatal dopamine content and modest 5-HT reduction 1 h after the last dose. MDMA does not therefore appear to be responsible for the acute monoamine release that follows its peripheral injection. 3. HHMA does not contribute to the acute MDMA-induced dopamine depletion as the acute central effects of MDMA and HHMA differed following i.p. injection. Both compounds induced hyperthermia, confirming that the acute dopamine depletion is not responsible for the temperature changes. 4. Peripheral administration of MDMA produced dopamine depletion 7 days later. Intrastriatal MDMA administration only produced a long-term loss of dopamine at much higher concentrations than those reached after the i.p. dose and therefore bears little relevance to the neurotoxicity. This indicates that the long-term effect is not attributable to the parent compound. HHMA also appeared not to be responsible as i.p. administration failed to alter the striatal dopamine concentration 7 days later. 5. HHMA was detected in plasma, but not in brain, following MDMA (i.p.), but it can cross the blood-brain barrier as it was detected in the brain following its peripheral injection. 6. The fact that the acute changes induced by i.p. or intrastriatal HHMA administration differed indicates that HHMA is metabolised to other compounds which are responsible for changes observed after i.p. administration.

Contrasting Fos expression induced by acute reboxetine and fluoxetine in the rat forebrain: neuroanatomical substrates for the antidepressant effect

RATIONALE

Antidepressants preferentially facilitating serotonin seem to be particularly effective for treating the anxiety and aggressive component of the depressive syndrome, whereas those with a noradrenergic profile seem to be more effective in reducing psychomotor retardation, although their overall antidepressant effects are about the same. However, the mechanism of this difference remains unknown.

OBJECTIVES

To investigate the neural substrate for the different therapeutic efficacies of fluoxetine and reboxetine, we examined the regional Fos immunoreactivity (Fos-ir) induced by the two agents.

METHODS

Male Wistar rats (290-330 g) were given a subcutaneous injection of fluoxetine (5 or 10 mg/kg), reboxetine (5 or 10 mg/kg) or saline. Two hours later, rats were perfused through the ascending aorta and their brains were processed for Fos immunohistochemistry. Fos-ir was quantified by counting the number of Fos-ir-positive nuclei in six areas of the forebrain.

RESULTS

The shell of the nucleus accumbens was the only region in which both fluoxetine and reboxetine equally increased Fos-ir expression. Fluoxetine particularly induced Fos-ir in the central nucleus of the amygdala. In contrast, reboxetine induced Fos-ir in the cingulate cortex area 3 and the lateral orbital cortex.

CONCLUSIONS

These results suggest that the shell region may be one possible target for the antidepressant effects of fluoxetine and reboxetine. Furthermore, the difference in their clinical effects may depend on their different target sites of action.

Previous exposure to (±) 3,4-methylenedioxymethamphetamine produces long-lasting alteration in limbic brain excitability measured by electroencephalogram spectrum analysis, brain metabolism and seizure susceptibility

Seizures represent the most common neurological emergency in ecstasy abusers; however, no study addressed whether (+/-) 3,4-methylenedioxymethamphetamine ("ecstasy") per se might produce long-lasting alterations in brain excitability related to a pro-convulsant effect. C57 Black mice were treated with three regimens of (+/-) 3,4-methylenedioxymethamphetamine (5mg/kg x 2 for 1, 2 or three consecutive days). Following the last dose of (+/-) 3,4-methylenedioxymethamphetamine, during a time interval of 8 weeks, the following procedures were carried out: 1) cortical electroencephalographic recordings, including power-spectrum analysis; 2) administration of sub-threshold doses of kainate; 3) measurement of regional [(14)C]2-deoxyglucose uptake; 4) monoamine assay. We demonstrate that all mice pre-treated with (+/-) 3,4-methylenedioxymethamphetamine showed long-lasting encephalographic changes with frequencies peaking at 3-4.5 Hz at the power-spectrum analysis. This is concomitant with latent brain hyperexcitability within selected limbic brain regions, as shown by seizure facilitation and long-lasting latent metabolic hyperactivity which can be unraveled by phasic glutamate stimulation. This study sheds new light into the brain targets of (+/-) 3,4-methylenedioxymethamphetamine and discloses the occurrence of (+/-) 3,4-methylenedioxymethamphetamine-induced latent hyperexcitability within limbic areas, while it might provide a model to study in controlled experimental conditions limbic seizures and status epilepticus in C57 Black mice. Persistent changes produced by (+/-) 3,4-methylenedioxymethamphetamine in limbic brain excitability might be responsible for seizures and limbic-related disorders in chronic (+/-) 3,4-methylenedioxymethamphetamine abusers.

The role of the sympathetic nervous system and uncoupling proteins in the thermogenesis induced by 3,4-methylenedioxymethamphetamine

Body temperature regulation involves a homeostatic balance between heat production and dissipation. Sympathetic agents such as 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) can disrupt this balance and as a result produce an often life-threatening hyperthermia. The hyperthermia induced by MDMA appears to result from the activation of the sympathetic nervous system (SNS) and the hypothalamic-pituitary-thyroid/adrenal axis. Norepinephrine release mediated by MDMA creates a double-edged sword of heat generation through activation of uncoupling protein (UCP3) along with alpha1- and beta3-adrenoreceptors and loss of heat dissipation through SNS-mediated vasoconstriction. This review examines cellular mechanisms involved in MDMA-induced thermogenesis from UCP activation to vasoconstriction and how these mechanisms are related to other thermogenic conditions and potential treatment modalities.

Regulation of affect by the lateral septum: implications for neuropsychiatry

Substantial evidence indicates that the lateral septum (LS) plays a critical role in regulating processes related to mood and motivation. This review presents findings from the basic neuroscience literature and from some clinically oriented research, drawing from behavioral, neuroanatomical, electrophysiological, and molecular studies in support of such a role, and articulates models and hypotheses intended to advance our understanding of these functions. Neuroanatomically, the LS is connected with numerous regions known to regulate affect, such as the hippocampus, amygdala, and hypothalamus. Through its connections with the mesocorticolimbic dopamine system, the LS regulates motivation, both by stimulating the activity of midbrain dopamine neurons and regulating the consequences of this activity on the ventral striatum. Evidence that LS function could impact processes related to schizophrenia and other psychotic spectrum disorders, such as alterations in LS function following administration of antipsychotics and psychotomimetics in animals, will also be presented. The LS can also diminish or enable fear responding when its neural activity is stimulated or inhibited, respectively, perhaps through its projections to the hypothalamus. It also regulates behavioral manifestations of depression, with antidepressants stimulating the activity of LS neurons, and depression-like phenotypes corresponding to blunted activity of LS neurons; serotonin likely plays a key role in modulating these functions by influencing the responsiveness of the LS to hippocampal input. In conclusion, a better understanding of the LS may provide important and useful information in the pursuit of better treatments for a wide range of psychiatric conditions typified by disregulation of affective functions.

Increased CRE-binding activity and tryptophan hydroxylase mRNA expression induced by 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") in the rat frontal cortex but not in the hippocampus

A single administration of either 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") or p-chloroamphetamine (PCA) produced a rapid and marked reduction of serotonin (5-HT) content in rat frontal cortex and hippocampus. In the cortex of MDMA-treated rats, 5-HT levels returned to control values 48 h after drug administration. This recovery was correlated with an induction of CRE-binding activity and an enhanced expression of tryptophan hydroxylase (TPH) mRNA, the rate-limiting enzyme in 5-HT biosynthesis, suggesting that MDMA may up-regulate the TPH gene through a CREB-dependent mechanism. In the cortex of PCA-treated rats, neither a recovery of 5-HT levels nor changes in DNA-binding or TPH mRNA were found at the same time point. In the hippocampus of rats receiving either PCA or MDMA a decrease in TPH mRNA levels was found at all times, along with a reduced CRE-binding at the 8-h time point. The results show region-specific effects of MDMA. In the frontal cortex, the increased TPH expression suggests a compensatory response to MDMA-induced loss of serotonergic function.

Neural correlates of cat odor-induced anxiety in rats: region-specific effects of the benzodiazepine midazolam

Cat odor elicits a profound defensive reaction in rats that is reduced by benzodiazepine drugs. The neural correlates of this phenomenon were investigated here using Fos immunohistochemistry. Rats received either midazolam (0.75 mg/kg, s.c.) or vehicle and were exposed to pieces of a collar that had been worn by a domestic cat or an unworn (dummy) collar. Cat odor caused midazolam-sensitive defensive behavioral responses, including avoidance of collar contact, inhibition of grooming, and prolonged rearing. Cat odor exposure induced Fos expression in the posterior accessory olfactory bulb (glomerular, mitral, and granule cell layers), with granule cell layer activation attenuated by midazolam. High basal Fos expression, and some cat odor-associated Fos expression, was evident in the main olfactory bulb (glomerular cell layer), and midazolam exerted a strong inhibitory effect in this region. Midazolam inhibited Fos expression in key limbic regions involved in pheromone transduction (medial amygdala and bed nucleus of the stria terminalis) and defensive behavior (prelimbic cortex, lateral septum, lateral and medial preoptic areas, and dorsal premammillary nucleus). However, midazolam failed to affect cat odor-related Fos expression in a range of key defense-related sites, including the ventromedial hypothalamic nucleus, paraventricular nucleus of the hypothalamus, periaqueductal gray, and cuneiform nucleus. These results indicate that midazolam exerts a region-specific effect on the neural substrates activated by predator odor, with effects in the lateral septum and dorsal premammillary nucleus likely to be of major importance. These findings also suggest the intriguing hypothesis that cat odor is processed by rats as a "pheromone-like" stimulus.

Effects of 3,4-methylenedioxymethamphetamine ('Ecstasy') on the jaw-opening reflex and on the alpha2-adrenoceptors which regulate this reflex in the anesthetized rat

Bruxism, principally jaw clenching, is frequently observed in users of the recreational drug 3,4-methylenedioxymethamphetamine (MDMA). It has been suggested that during bruxism a reduction of the activity of oral protective reflexes occurs. In this study we investigated the effects of intravenously administered MDMA on the digastric electromyographic responses elicited by orofacial electrical stimulation in the rat. We also assessed the effects of either the administration of a single dose (20 mg kg(-1), s.c.) or repeated doses of MDMA (same dose, twice a day, for 4 d) on the jaw-opening reflex (JOR) and on the sensitivity of the alpha(2)-adrenoceptors which, in an inhibitory way, regulate it. Increasing doses of MDMA (1-29440 micro g kg(-1)) induced an incomplete inhibition of JOR and 50% inhibition (ED(50)) at 2550 micro g kg(-1); maximal inhibition was 88%. The repeated treatment with MDMA led to an enhancement of the inhibition of JOR induced by the alpha(2)-agonist, clonidine (ED(50) was reduced by 77%), indicating an increased sensitivity of the alpha(2)-adrenoceptors. This study shows that the intravenous administration of MDMA reduces the JOR while repeated doses of the drug enhance the inhibitory noradrenergic mechanisms which regulate the reflex. The results also allow speculation that a reduction of JOR may underlie the occurrence of episodes of bruxism in MDMA users.

MDMA (Ecstasy) controls in concert a group of genes involved in GABA neurotransmission

In several countries, 3,4-methylenedioxymethamphetamine (MDMA) is currently the most abundant psychoactive recreational drug. MDMA induces numerous neuropsychiatric behaviors, serotonergic neuron degeneration, programmed death of cultured cells, hyperthermia and occasional fatality. Using gene expression analysis in MDMA-treated mice, we identified changes in gamma-amino butyric acid (GABA) transporters and synaptotagmins I and IV. Additional experiments showed decreases in mRNAs encoding septin and dystrophin. Although belonging to different gene families, it is striking that these four protein groups are implicated in neurotransmission of GABA, a major inhibitory neurotransmitter involved in thermoregulation. MDMA may control these genes in a combined fashion, assigning GABA a pivotal role in MDMA activities.