Post-myocardial infarction depression.
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Antidepressive Agents↗
Biomedical subjects
U D McCann
Publications and source records attributed to U D McCann.
Use of MDMA and other illicit drugs by young adult males in northern Spain. A five-year study.
AIM: To measure the prevalence of 3,4-methylenedioxymethamphetamine (MDMA) and other drug use in young males entering compulsory military service in Asturias (northern Spain) and to define trends in MDMA use in this group during the period from 1995 to 1999. We also sought to determine whether MDMA users have distinct personality features or higher levels of sensation seeking. METHODS: 3,634 conscripts [mean age (SD) = 20.19 years (2.52)] who entered military service during the period between 1995 and 1999 were evaluated using the World Health Organization (WHO) questionnaire for drug consumption, the Eysenck Personality Questionnaire-A (EPQ-A), and the Zuckerman Sensation Seeking Scale. RESULTS AND CONCLUSIONS: The prevalence of lifetime, previous year and previous month MDMA use among military recruits between 1995 and 1999 was 10.9, 7.8 and 4.5%, ranking fifth among illicit drugs ever used. Once individuals used MDMA for the first time, they were likely to use it again, with 71% of individuals who had ever used MDMA reporting that they had used it during the past year (ranking second only to hallucinogens), and 41% reporting having used it in the last month. Compared to recruits who had never used MDMA (but who may have used other illicit drugs), MDMA users had a more extensive drug abuse history. Recruits who had used MDMA during the year prior to study had significantly higher scores on the Neuroticism and Psychoticism Subscales of the EPQ-A, and reported higher levels of sensation seeking.
Adult↗
Assessing long-term effects of MDMA (Ecstasy).
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Animals↗
Regional cerebral blood flow correlated with flashback intensity in patients with posttraumatic stress disorder.
BACKGROUND: Nuclear imaging studies have examined cerebral blood flow (rCBF) in subjects with posttraumatic stress disorder (PTSD) using symptom evocation paradigms. To date, no such studies have investigated rCBF as related to subjects' reports of flashback intensity. METHODS: Subjects with varying traumatic histories and longstanding PTSD were studied using [15O]-H2O positron emission tomography with an auditory script of their traumatic event. Eight subjects had three resting scans followed by their script and additional scans. Heart rate responses as well as the presence of flashbacks and their intensity were recorded. rCBF was correlated with flashback intensity in each subject's scan. Combined analysis of all subjects' data yielded common regions related to the flashback experience. RESULTS: rCBF correlated directly with flashback intensity in the brainstem, lingula, bilateral insula, right putamen and left hippocampal and perihippocampal, somatosensory and cerebellar regions. Inverse correlations with rCBF were found in bilateral dorsolateral prefrontal, right fusiform and right medial temporal cortices. CONCLUSIONS: This study correlated flashback intensity and rCBF in a group of patients with chronic PTSD suggesting involvement of brainstem, and areas associated with motor control, complex visual/spatial cues and memory.
Adult↗
"Ecstasy" and serotonin neurotoxicity: new findings raise more questions.
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Brain Chemistry↗
A murine dopamine neuron-specific cDNA library and microarray: increased COX1 expression during methamphetamine neurotoxicity.
Due to brain tissue heterogeneity, the molecular genetic profile of any neurotransmitter-specific neuronal subtype is unknown. The purpose of this study was to purify a population of dopamine neurons, construct a cDNA library, and generate an initial gene expression profile and a microarray representative of dopamine neuron transcripts. Ventral mesencephalic dopamine neurons were purified by fluorescent-activated cell sorting from embryonic day 13.5 transgenic mice harboring a 4.5-kb rat tyrosine hydroxylase promoter-lacZ fusion. Nine-hundred sixty dopamine neuron cDNA clones were sequenced and arrayed for use in studies of gene expression changes during methamphetamine neurotoxicity. A neurotoxic dose of methamphetamine produced a greater than twofold up-regulation of the mitochondrial cytochrome c oxidase polypeptide I transcript from adult mouse substantia nigra at 12 h posttreatment. This is the first work to describe a gene expression profile for a neuronal subtype and to identify gene expression changes during methamphetamine neurotoxicity.
3,4-Dihydroxyphenylacetic Acid↗
Experimental studies on 3,4-methylenedioxymethamphetamine (MDA, "ecstasy") and its potential to damage brain serotonin neurons.
A number of drugs that fall into the broad category of "ring-substituted amphetamines" have been found to be neurotoxic toward brain monoamine neurons in animals. Several of these drugs, including 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") and methamphetamine ("speed") and fenfluramine ("Pondimin") have been used or abused by humans. A growing body of evidence indicates that humans, like animals, are susceptible to substituted amphetamine-induced neurotoxic injury, and that consequences of this injury can be subtle. This article will review the effects of ring-substituted amphetamine analogs on brain monoamine neurons, using MDMA as the prototype. Studies documenting MDMA neurotoxic potential toward brain serotonin (5-HT) neurons in animals are summarized first. Human MDMA studies are then discussed, beginning with a consideration of methodological challenges in evaluating the status of 5-HT neurons in the living human brain. Recent findings indicating possible functional alterations in brain serotonergic systems in humans with a history of extensive MDMA exposure are then presented, including some new findings on sleep and personality in abstinent MDMA users.
Journal Article↗
Summary of a National Institute of Mental Health workshop: developing animal models of anxiety disorders.
RATIONALE: There exists a wide range of animal models and measures designed to assess anxiety or fearfulness. However, the relationship between these models and clinical anxiety symptoms and syndromes is unclear. The National Institute of Mental Health convened a workshop to discuss the relationship between existing behavioral models of anxiety and the clinical profile of anxiety disorders. A second goal of this workshop was to outline various approaches towards modeling components of anxiety disorders. OBJECTIVES: To briefly describe epidemiological and behavioral manifestations of clinical anxiety syndromes and how they relate to commonly employed animal models of anxiety. To describe approaches and considerations for developing, improving, and adapting anxiety models to better understand the neurobiology of anxiety. METHODS: Clinicians, psychiatrists and clinical and basic neuroscientists presented data exemplifying different approaches towards understanding anxiety and the role of animal models. Panel members outlined what they considered to be critical issues in developing and employing animal models of anxiety. RESULTS: This review summarizes the discussions and conclusions of the workshop including recommendations for improving upon existing models and strategies for developing novel models. CONCLUSIONS: The probability of developing comprehensive animal models that accurately reflect the relative influences of factors contributing to anxiety disorder syndromes is quite low. However, ample opportunity remains to better define and extend existing models and behavioral measures related to specific processes that may be disrupted in anxiety disorders and to develop new models that consider the impact of combined factors in determining anxious behaviors.
Animals↗
Caveat emptor: editors beware.
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Animals↗
Evidence against an essential role of endogenous brain dopamine in methamphetamine-induced dopaminergic neurotoxicity.
The present studies examined the role of endogenous dopamine (DA) in methamphetamine (METH)-induced dopaminergic neurotoxicity while controlling for temperature-related neuroprotective effects of the test compounds, reserpine and alpha-methyl-p-tyrosine (AMPT). To determine if the vesicular pool of DA was essential for the expression of METH-induced DA neurotoxicity, reserpine (3 mg/kg, given iintraperitoneally 24-26 h prior to METH) was given prior to a toxic dose regimen of METH. Despite severe striatal DA deficits during the period of METH exposure, mice treated with reserpine prior to METH developed long-term reductions in striatal DA axonal markers, suggesting that vesicular DA stores were not crucial for the development of METH neurotoxicity, but leaving open the possibility that cytoplasmic DA might be involved. To evaluate this possibility, cytoplasmic DA stores were depleted with AMPT prior to METH administration. When this study was carried out at 28 degrees C, complete neuroprotection was observed, likely due to lingering effects on core temperature because when the same study was repeated at 33 degrees C (to eliminate AMPT's hypothermic effect in METH-treated animals), the previously observed neuroprotection was no longer evident. In the third and final set of experiments, mice were pretreated with a combination of reserpine and AMPT, to deplete both vesicular and cytoplasmic DA pools, and to reduce striatal DA levels to negligible values during the period of METH administration (< 0.05%). When core temperature differences were eliminated by raising ambient temperature, METH-induced DA neurotoxic changes were evident in mice pretreated with reserpine and AMPT. Collectively, these findings bring into question the view that endogenous DA plays an essential role in METH-induced DA neurotoxicity.
3,4-Dihydroxyphenylacetic Acid↗
Inhibitors of Na(+)/H(+) and Na(+)/Ca(2+) exchange potentiate methamphetamine-induced dopamine neurotoxicity: possible role of ionic dysregulation in methamphetamine neurotoxicity.
Although the neurotoxic potential of methamphetamine (METH) is well established, underlying mechanisms have yet to be identified. In the present study, we sought to determine whether ionic dysregulation was a feature of METH neurotoxicity. In particular, we reasoned that if METH impairs the function of Na(+)/H(+) and/or Na(+)/Ca(2+) antiporters by compromising the inward Na(+) gradient [via prolonged DA transporter (DAT) activation and Na(+)/K(+) ATPase inhibition], then amiloride (AMIL) and other inhibitors of Na(+)/H(+) and/or Na(+)/Ca(2+) exchange would potentiate METH neurotoxicity. To test this hypothesis, mice were treated with METH alone or in combination with AMIL or one of its analogs; 1 week later, the animals were killed for studies of dopamine (DA) neuronal integrity. AMIL markedly potentiated the toxic effect of METH on DA neurons. Potentiation was not caused by increased core temperature, enhanced DAT activity or higher METH brain levels. The DAT inhibitor, WIN-35,428, protected completely against METH-induced DA neurotoxicity in AMIL pretreated animals, suggesting that the potentiating effects of AMIL require a METH/DAT interaction. Findings with METH and AMIL were extended to six other AMIL analogs (MIA, EIPA, DIMA, BENZ, BEP, DiCBNZ), another species (rats), and neuronal type (5-HT neurons). These results support the notion that ionic dysregulation may play a role in METH neurotoxicity.
Amiloride↗
Effect of temperature on dopamine transporter function and intracellular accumulation of methamphetamine: implications for methamphetamine-induced dopaminergic neurotoxicity.
Hyperthermia exacerbates and hypothermia attenuates methamphetamine (METH)-induced dopamine (DA) neurotoxicity. The mechanisms underlying these temperature effects are unknown. Given the essential role of the DA transporter (DAT) in the expression of METH-induced DA neurotoxicity, we hypothesized that the effect of temperature on METH-induced DA neurotoxicity is mediated, at least in part, at the level of the DAT. To test this hypothesis, the effects of small, physiologically relevant temperature changes on DAT function were evaluated in two types of cultured neuronal cells: (1) a neuroblastoma cell line stably transfected with human DAT cDNA and (2) rat embryonic mesencephalic primary cells that naturally express the DAT. Temperatures for studies of DAT function were selected based on core temperature measurements in animals exposed to METH under usual ambient (22 degrees C) and hypothermic (6 degrees C) temperature conditions, where METH neurotoxicity was fully expressed and blocked, respectively. DAT function, determined by measuring accumulation of radiolabeled DA and 1-methyl-4-phenylpyridinium (MPP(+)), was found to directly correlate with temperature, with higher levels of substrate uptake at 40 degrees C, intermediate levels at 37 degrees C, and lower levels at 34 degrees C. DAT-mediated accumulation of METH also directly correlated with temperature, with greater accumulation at higher temperatures. These findings indicate that relatively small, physiologically relevant changes in temperature significantly alter DAT function and intracellular METH accumulation, and suggest that the effect of temperature on METH-induced DA neurotoxicity is mediated, at least in part, at the level of the DAT.
1-Methyl-4-phenylpyridinium↗
Toxicodynamics and long-term toxicity of the recreational drug, 3, 4-methylenedioxymethamphetamine (MDMA, 'Ecstasy').
The recreational drug, (+/-)3,4-methylenedioxymethamphetamine (MDMA, 'Ecstasy'), is a potent serotonin (5-HT) neurotoxin in animals. Whether humans who use MDMA incur 5-HT neural injury is unknown. The present studies utilized positron emission tomography (PET) in conjunction with the 5-HT transporter ligand, [11C]McN-5652 to assess the status of brain 5-HT neurons in human MDMA users. Like nonhuman primates treated with neurotoxic doses of MDMA, humans with a history of MDMA use showed lasting decrements in global brain [11C]McN-5652 binding, with decreases in [11C]McN-5652 binding positively correlated to the extent of previous MDMA use. These results suggest that human MDMA use results in brain 5-HT neurotoxicity.
Animals↗
(+/-)3,4-Methylenedioxymethamphetamine ('Ecstasy')-induced serotonin neurotoxicity: studies in animals.
The popular recreational drug, (+/-)3, 4-methylenedioxymethamphetamine (MDMA; 'Ecstasy') is a potent and selective brain serotonin (5-HT) neurotoxin in animals. MDMA-induced 5-HT neurotoxicity can be demonstrated using a variety of neurochemical, neuroanatomical and, more recently, functional measures of 5-HT neurons. Although the neurotoxic effects of MDMA in animals are widely accepted, the relevance of the animal data to human MDMA users has been questioned, largely because dosages of drugs used in animals are perceived as being much higher than those used by humans. In the present paper, we review the extensive body of data demonstrating that MDMA produced toxic effects on brain 5-HT neurons in animals and present new data indicating that levels of the type 2 vesicular monoamine transporter are reduced in MDMA-treated animals, providing further indication of MDMA's 5-HT neurotoxic potential. Further, we demonstrate, using principles of interspecies scaling, that dosages of MDMA known to be neurotoxic in animals fall squarely in the range of dosages used typically by recreational MDMA users.
Animals↗
(+/-)3,4-Methylenedioxymethamphetamine ('Ecstasy')-induced serotonin neurotoxicity: clinical studies.
(+/-)3,4-Methylenedioxymethamphetamine (MDMA, 'Ecstasy') is a brain serotonergic neurotoxin in experimental animals, including nonhuman primates. It is also an increasingly popular recreational drug of abuse, and doses of MDMA that are used recreationally overlap with those that produce serotonin (5-HT) neurotoxicity in animals. Studies in human MDMA users probing for evidence of brain serotonergic neurotoxicity indicate that some MDMA users may incur MDMA-related 5-HT neural injury and, possibly, functional sequelae. In particular, MDMA users have selective decrements in cerebrospinal fluid 5-hydroxyindoleacetic acid and brain 5-HT transporters, similar to nonhuman primates with documented MDMA-induced neurotoxicity. Functional abnormalities seen in MDMA users that may be related to 5- HT injury include cognitive deficits, altered sleep architecture, altered neuroendocrine function, altered behavioral responses to 5-HT selective drugs, and increased impulsivity. Additional studies in animals, as well as longitudinal and epidemiological studies in MDMA users, are required to confirm and extend the present data, and to determine whether MDMA users are at increased risk for developing neuropsychiatric illness as they age.
Animals↗
Altered serotonin innervation patterns in the forebrain of monkeys treated with (+/-)3,4-methylenedioxymethamphetamine seven years previously: factors influencing abnormal recovery.
The recreational drug (+/-)3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") is a potent and selective brain serotonin (5-HT) neurotoxin in animals and, possibly, in humans. The purpose of the present study was to determine whether brain 5-HT deficits persist in squirrel monkeys beyond the 18-month period studied previously and to identify factors that influence recovery of injured 5-HT axons. Seven years after treatment, abnormal brain 5-HT innervation patterns were still evident in MDMA-treated monkeys, although 5-HT deficits in some regions were less severe than those observed at 18 months. No loss of 5-HT nerve cell bodies in the rostral raphe nuclei was found, indicating that abnormal innervation patterns in MDMA-treated monkeys are not the result of loss of a particular 5-HT nerve cell group. Factors that influence recovery of 5-HT axons after MDMA injury are (1) the distance of the affected axon terminal field from the rostral raphe nuclei, (2) the degree of initial 5-HT axonal injury, and possibly (3) the proximity of damaged 5-HT axons to myelinated fiber tracts. Additional studies are needed to better understand these and other factors that influence the response of primate 5-HT neurons to MDMA injury and to determine whether the present findings generalize to humans who use MDMA for recreational purposes.
Amygdala↗
Cognitive performance in (+/-) 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") users: a controlled study.
RATIONALE: (+/-) 3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") is an amphetamine analog and drug of abuse. In animals, MDMA damages brain serotonin (5-HT) neurons at doses that overlap with those used recreationally by some humans. To date, few functional sequelae of MDMA-induced 5-HT damage have been identified. OBJECTIVE: Since serotonin is thought to be involved in cognitive processes, and since previous studies have reported verbal and visual memory deficits in MDMA users, the present study sought to determine whether other cognitive processes are influenced by previous exposure to MDMA. METHODS: Twenty-two MDMA users who had not used MDMA for at least 3 weeks and 23 control subjects were tested repeatedly with a computerized cognitive performance assessment battery while participating in a 5-day controlled inpatient study. Cerebrospinal fluid (CSF) measures of monoamine metabolites were also collected as an index of brain monoaminergic function. RESULTS: MDMA users and controls were found to perform similarly on several cognitive tasks. However, MDMA subjects had significant performance deficits on a sustained attention task requiring arithmetic calculations, a task requiring complex attention and incidental learning, a task requiring short term memory and a task of semantic recognition and verbal reasoning. MDMA users also had significant selective decreases in CSF 5-HIAA. CONCLUSIONS: The present CSF data provide further evidence that MDMA is neurotoxic to brain 5-HT neurons in humans, and the behavioral data suggest that brain 5-HT injury is associated with subtle, but significant, cognitive deficits.
Adult↗
Altered neuroendocrine and behavioral responses to m-chlorophenylpiperazine in 3,4-methylenedioxymethamphetamine (MDMA) users.
RATIONALE: (+/-) 3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy") is a popular drug of abuse and a brain serotonin neurotoxin in animals. Growing evidence indicates that humans are also susceptible to MDMA's neurotoxic effects, although few functional consequences of MDMA-induced 5-HT damage have been identified. OBJECTIVE: The present study sought to determine whether possible differences between MDMA users and control subjects could be unmasked by utilizing a pharmacological challenge with the mixed 5-HT agonist, meta-chlorophenylpiperazine (m-CPP). It was postulated that 5-HT neurotoxicity in MDMA users would be associated with altered 5-HT responsivity, exemplified by altered physiological and behavioral responses to m-CPP. METHODS: Twenty-five MDMA users who had not taken MDMA for at least 3 weeks and 25 controls received intravenous placebo (normal saline) and m-CPP (0.08 mg/kg) in a fixed order, single blind design. Repeated measures of mood, physical symptoms, and blood samples for neuroendocrine analyses were collected during the 90 min after each infusion. RESULTS: MDMA users reported more positive and fewer negative emotions and physical symptoms following m-CPP than controls, and were significantly less likely to report an m-CPP-induced panic attack. Male MDMA users had diminished cortisol and prolactin responses to m-CPP. CONCLUSIONS: The present data indicate that MDMA users have alterations in 5-HT neuronal function, possibly as a consequence of MDMA-induced brain serotonin neural injury.
Adult↗