3,4-Methylenedioxymethamphetamine (MDMA or "Ecstasy") is a psychoactive and hallucinogenic drug of abuse. MDMA has been shown to produce neurotoxicity both in animals and humans. MDMA and other amphetamines induce serotonergic and dopaminergic terminal neurotoxicity and also neurodegeneration in areas including the cortex, hippocampus, striatum and thalamus. Herein, we investigated the mechanisms involved in MDMA-induced neurotoxicity to neuronal serum free cultures from rat cortex. The hyperthermic effect produced by MDMA has been shown to be a clinically relevant aspect for the neurotoxic events. Thus, MDMA-induced toxicity to cortical neurons was evaluated both under normothermic (36.5 degrees C) and hyperthermic (40 degrees C) conditions. Our findings showed that MDMA produced neuronal apoptosis, accompanied by activation of caspase 3, in a concentration dependent manner. MDMA neurotoxicity was completely prevented by pre-treatment with a 5-HT(2A)-receptor antibody, which acted as an "irreversible non-competitive antagonist" of this receptor. Furthermore, MDMA depleted intracellular glutathione (GSH) levels in a concentration dependent manner, an effect that was attenuated by Ketanserin, a competitive 5-HT(2A)-receptor antagonist. Accordingly, N-acetylcysteine, an antioxidant and GSH precursor, also reduced MDMA-induced toxicity. Specific inhibitors of the inducible and neuronal nitric oxide synthase (NOS) partially prevented MDMA neurotoxicity, ascertaining the involvement of reactive nitrogen species, in the toxic effect. In conclusion, direct MDMA 5-HT(2A)-receptor stimulation produces intracellular oxidative stress that leads to neuronal apoptosis accompanied by caspase 3 activation.
"Nevertheless, studies in hippocampal cultured neurons (400 µM, 24 h) found no changes in both cytosolic and mitochondrial cytochrome c content, but increased cas- pase-8-and caspase-3-like activities after 48 h of exposure (Capela et al. 2013), also suggesting a role for the extrinsic pathway in apoptosis activation. Other reports in cultured cortical neurons from rat or SH-SH5Y-differentiated cells have also revealed increased caspase-3 activity following exposure to MDMA (200–800 µM, for 48 h) (Capela et al. 2007a) or its metabolites N-Me-α-MeDA (100 µM, 24 h) (Barbosa et al. 2014a), 5-(NAC)-α-MeDA (200 µM, 24 h) (Capela et al. 2007b), or 5-(NAC)-N-Me-α-MeDA (200 µM, 24 h) (Capela et al. 2007b) or to the mixture of MDMA and six of its major in vivo metabolites, each compound at a equimolar concentration of 10 µM, for 24 h (Barbosa et al. 2014b). Nevertheless, a direct involvement of mitochondrial-dependent pathways in this effect was not established. "
[Show abstract][Hide abstract] ABSTRACT: Amphetamines are a class of psychotropic drugs with high abuse potential, as a result of their stimulant, euphoric, emphathogenic, entactogenic, and hallucinogenic properties. Although most amphetamines are synthetic drugs, of which methamphetamine, amphetamine, and 3,4-methylenedioxymethamphetamine ("ecstasy") represent well-recognized examples, the use of natural related compounds, namely cathinone and ephedrine, has been part of the history of humankind for thousands of years. Resulting from their amphiphilic nature, these drugs can easily cross the blood-brain barrier and elicit their well-known psychotropic effects. In the field of amphetamines' research, there is a general consensus that mitochondrial-dependent pathways can provide a major understanding concerning pathological processes underlying the neurotoxicity of these drugs. These events include alterations on tricarboxylic acid cycle's enzymes functioning, inhibition of mitochondrial electron transport chain's complexes, perturbations of mitochondrial clearance mechanisms, interference with mitochondrial dynamics, as well as oxidative modifications in mitochondrial macromolecules. Additionally, other studies indicate that amphetamines-induced neuronal toxicity is closely regulated by B cell lymphoma 2 superfamily of proteins with consequent activation of caspase-mediated downstream cell death pathway. Understanding the molecular mechanisms at mitochondrial level involved in amphetamines' neurotoxicity can help in defining target pathways or molecules mediating these effects, as well as in developing putative therapeutic approaches to prevent or treat the acute- or long-lasting neuropsychiatric complications seen in human abusers.
Archives of Toxicology 03/2015; DOI:10.1007/s00204-015-1478-9 · 5.98 Impact Factor
"as both in vivo ( Pereira et al . , 2006 ; Wan et al . , 2006 ) and in vitro ( Jimenez et al . , 2004 ; Capela et al . , 2006b , 2007a ) . We have previously reported that MDMA ( con - centration range of 200 – 800 lM ) treatment in an acute exposure model , promoted a reduction in GSHt levels in cortical neuronal cultures after 48 h of exposure ( Capela et al . , 2007a ) ."
[Show abstract][Hide abstract] ABSTRACT: Amphetamine-like psychostimulants (ATS) are used worldwide by millions of patients for several psychiatric disorders. Amphetamine (AMPH) and "ecstasy" (3,4-methylenedioxymethamphetamine or MDMA) are common drugs of abuse. The impact of chronic ATS exposure to neurons and brain aging is still undisclosed. Current neuronal culture paradigms are designed to access acute ATS toxicity. We report for the first time a model of chronic exposure to AMPH and MDMA using long-term rat cortical cultures. In two paradigms, amphetamines were applied to neurons at day one in vitro (DIV) (0, 1, 10 and 100 μM of each drug) up to 28 days (200 μM was applied to cultures up to 14DIV). Our reincubation protocol assured no decrease in the neuronal mediums' drug concentration. Chronic exposure of neurons to concentrations equal to or above 100 μM of ATS up to 28DIV promoted significant mitochondrial dysfunction and elicited neuronal death, which was not prevented by glutamate receptor antagonists at 14DIV. Amphetamines failed to promote accelerated senescence as no increase in β-galactosidase activity at 21DIV was found. In younger cultures (4 or 8DIV), AMPH promoted mitochondrial dysfunction and neuronal death earlier than MDMA. Overall, AMPH proved more toxic and was the only drug that decreased intraneuronal glutathione levels. Meanwhile, caspase 3 activity increased for either drug at 200 μM in younger cultures at 8DIV, but not at 14DIV. At 8DIV, ATS promoted a significant change in the percentage of neurons and astroglia present in culture, promoting a global decrease in the number of both cells. Importantly, concentrations equal to or below 10 μM of either drug did not promote neuronal death or oxidative stress. Our paradigm of neuronal cultures long-term exposure to low micromolar concentrations of amphetamines closely reproduces the in vivo scenario, being valuable to study the chronic impact of ATS.
"Ischemia-related apoptotic death and the penumbra area have recently become more popular subjects and are now the focal point of many studies. Several articles emphasized the relationship between 5-hydroxytryptamine-2 (5-HT2) agonist and antagonists and apoptotic cell death16,17,27,49,55,65). We therefore planned our study believing that quetiapine, a dibenzothiazepine derivative atypical antipsychotic drug, could decrease apoptotic cell death and the negative effects of secondary injury in cerebral ischemia while also preventing the neuropsychiatric complications caused by this ischemia. "
[Show abstract][Hide abstract] ABSTRACT: This study was undertaken in the belief that the atypical antipsychotic drug quetiapine could prevent apoptosis in the penumbra region following ischemia, taking into account findings that show 5-hydroxytryptamine-2 receptor blockers can prevent apoptosis.
We created 5 groups, each containing 6 animals. Nothing was done on the K-I group used for comparisons with the other groups to make sure adequate ischemia had been achieved. The K-II group was sacrificed on the 1st day after transient focal cerebral ischemia and the K-III group on the 3rd day. The D-I group was administered quetiapine following ischemia and sacrificed on the 1st day while the D-II group was administered quetiapine every day following the ischemia and sacrificed on the 3rd day. The samples were stained with the immunochemical TUNEL method and the number of apoptotic cells were counted.
There was a significant difference between the first and third day control groups (K-II/K-III : p=0.004) and this indicates that apoptotic cell death increases with time. This increase was not encountered in the drug groups (D-I/D-II : p=1.00). Statistical analysis of immunohistochemical data revealed that quetiapine decreased the apoptotic cell death that normally increased with time.
Quetiapine is already in clinical use and is a safe drug, in contrast to many substances that are used to prevent ischemia and are not normally used clinically. Our results and the literature data indicate that quetiapine could help both as a neuronal protector and to resolve neuropsychiatric problems caused by the ischemia in cerebral ischemia cases.
Journal of Korean Neurosurgical Society 07/2013; 54(1):1-7. DOI:10.3340/jkns.2013.54.1.1 · 0.64 Impact Factor
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