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Altered gene expression in frontal cortex and midbrain of 3,4-methylenedioxymethamphetamine (MDMA) treated mice:
1Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
Abstract:
Changes in gene expression were examined in the brain of mice treated with a drug of abuse, 3,4-methylenedioxymethamphetamine (MDMA, also called Ecstasy). Frontal cortex and midbrain mRNA, analyzed by differential display polymerase chain reaction (DD-PCR) method, showed an altered expression of several cDNAs, 11 of which were isolated, cloned and sequenced. The sequence of one MDMA-induced mRNA corresponds (99.3%) to the mouse gamma-amino butyric acid (GABA) transporter 1 (mGAT1). The established involvement of GABA neurotransmission in the activity of several abused drugs prompted us to focus herein on MDMA effect on the GABA transporter gene family. Semi-quantitative PCR analysis with primers selective to the reported mGAT1 sequence confirmed that MDMA treatment increased mGAT1 expression. Time-course study of the expression of the three GABA transporter subtypes showed that MDMA induced a differential temporal activation of mGAT1 and mGAT4, but had no effect on mGAT2. Quantitative real-time PCR further proved the increased expression of mGAT1 and mGAT4 upon MDMA treatment. Western immunoblotting with anti-GAT1 antibodies showed that MDMA also increased GAT1 protein levels, suggesting that neurotransmission of GABA was altered. MDMA effect was also verified in serotonin transporter knockout (-/-) mice that are insensitive behaviorally to MDMA; the drug did not increase GAT1 protein level in these mutants. In mice, tiagabine and NO-711, inhibitors of GABA transporters, restrained MDMA-induced acute toxicity and death. These results should facilitate novel approaches to prevent deleterious effects, including fatality, induced by MDMA and similar abused psychostimulants.
Insights
MDMA (Ecstasy) alters gene expression in mouse brains, increasing GABA transporter 1 (GAT1) and GAT4 levels. Inhibiting these transporters reduced MDMA toxicity, suggesting new therapeutic targets for stimulant abuse.
Area of Science:
- Neuroscience
- Pharmacology
- Genetics
Background:
- 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy) is a widely abused psychostimulant.
- GABAergic neurotransmission is implicated in the effects of various drugs of abuse.
- Understanding MDMA's molecular targets is crucial for developing interventions.
Purpose of the Study:
- To investigate the impact of MDMA on gene expression in the mouse brain, specifically focusing on GABA transporter genes.
- To determine if MDMA-induced changes in GABA transporter expression correlate with its acute toxicity.
Main Methods:
- Differential display polymerase chain reaction (DD-PCR) to identify altered gene expression.
- Semi-quantitative and quantitative real-time PCR to analyze GABA transporter subtype expression.
- Western immunoblotting to assess protein levels of GABA transporter 1 (GAT1).
- Studies in serotonin transporter knockout mice and administration of GABA transporter inhibitors (tiagabine, NO-711).
Main Results:
- MDMA treatment significantly increased the expression of mouse gamma-amino butyric acid (GABA) transporter 1 (mGAT1) and mGAT4 mRNA.
- MDMA also elevated GAT1 protein levels, indicating altered GABAergic neurotransmission.
- These effects were not observed in serotonin transporter knockout mice.
- Inhibitors of GABA transporters, tiagabine and NO-711, attenuated MDMA-induced toxicity and lethality in mice.
Conclusions:
- MDMA uniquely modulates the expression of specific GABA transporter subtypes in the brain.
- The observed increase in GAT1 and GAT4 expression is linked to MDMA's acute toxicity.
- Targeting GABA transporters may offer a novel therapeutic strategy to mitigate the harmful effects of MDMA and related psychostimulants.