Bucladesine Attenuates Spatial Learning and Hippocampal Mitochondrial Impairments Induced by 3, 4-Methylenedioxymethamphetamine (MDMA)

The Effect of Physical Exercise Pretreatment on Spatial Memory and Learning and Function of Mitochondria in the Brain in Type 2 Diabetic Rats

Background

The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide, and this issue is one of the major concerns in the pending years. T2DM causes numerous complications, including cognition, learning, and memory impairments. The positive effect of physical exercise as a popular approach has been shown in many chronic diseases. Further, the improvement effects of exercise on cognition and memory impairment have been noticed.

Objectives

This study examines the possible preventative effects of physical exercise on spatial memory attenuation and brain mitochondrial dysfunction caused by T2DM.

Methods

Male Wistar rats received treadmill exercise (30 min per day, five days per week for two or four weeks). Then, T2DM was induced by a high-fat diet and an injection of streptozotocin (30 mg/kg). Spatial learning and memory were assessed by the Morris water maze test. Further, brain mitochondrial function, including reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP), mitochondrial swelling, outer membrane damage, cytochrome c release, and ADP/ATP ratio, were measured.

Results

Impaired spatial memory in T2DM rats was observed. Furthermore, brain mitochondrial dysfunction was demonstrated proved by increased ROS generation, MMP collapse, mitochondrial swelling, outer membrane damage, cytochrome c release, and ADP/ATP ratio. Conversely, physical exercise, before diabetes onset, significantly ameliorated spatial memory impairment and brain mitochondrial dysfunction.

Conclusions

This study reveals that physical exercise could prevent diabetes-induced spatial memory impairment. Moreover, it could ameliorate brain mitochondrial dysfunction as one of the possible underlying mechanisms of spatial memory impairment in T2DM.

A review on the mitochondrial toxicity of “ecstasy” (3,4-methylenedioxymethamphetamine, MDMA)

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in vitro and in vivo studies on MDMA mitochondria toxicity are revised.

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MDMA causes ATP depletion and inhibition of mitochondrial complexes.

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MDMA or its metabolites impair mitochondrial trafficking in vitro.

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MDMA evokes deletion on mitochondrial DNA in vivo.

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A direct translation to humans is hampered by the doses and concentrations of MDMA.

3,4-Methylenedioxymethamphetamine (MDMA or “ecstasy”) is a drug of abuse used by millions worldwide. MDMA human abuse and dependence is well described, but addictive properties are not always consistent among studies. This amphetamine is a substrate type releaser, binding to monoamine transporters, leading to a pronounced release of serotonin and noradrenaline and to a minor extent dopamine. The toxicity of MDMA is well studied at the pre-clinical level, with neurotoxicity and hepatotoxicity being particularly described.

In this review, we describe the most relevant MDMA effects at the mitochondrial level found in in vitro and in vivo models, these later conducted in mice and rats. Most of these reports focus on the mitochondria of brain or liver. In in vitro models, MDMA causes depletion of ATP levels and inhibition of mitochondrial complex I and III, loss in mitochondrial membrane potential (ΔΨm) and induction of mitochondrial permeability transition. The involvement of mitochondria in the apoptotic cell death evoked by MDMA has also been shown, such as the release of cytochrome c. Additionally, MDMA or its metabolites impaired mitochondrial trafficking and increased the fragmentation of axonal mitochondria. In animal studies, MDMA decreased mitochondrial complex I activity and decreased ATP levels. Moreover, MDMA-evoked oxidative stress has been shown to cause deletion on mitochondrial DNA and impairment in mitochondrial protein synthesis.

Although the concentrations and doses used in some studies do not always correlate to the human scenario, the mitochondrial abnormalities evoked by MDMA are well described and are in part responsible for its mechanism of toxicity.