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Increased anxiety in rats after 3,4-methylenedioxymethamphetamine: association with serotonin depletion
Clint G Gurtman1, Kirsten C Morley, Kong M Li
1Department of Psychology, University of Sydney, NSW 2006, Sydney, Australia.
Abstract:
The long-term behavioural and neurotoxic effects of 3,4-methlyenedioxymethampthetamine (MDMA, "Ecstasy") were examined in rats. Rats were given MDMA (5 mg/kg i.p. once per hour for 4 h) or vehicle injections on each of two consecutive days at an ambient temparature of 28 degrees C. MDMA caused acute hyperthermia and locomotor hyperactivity on both days. Four and six weeks after drug administration the rats previously treated with MDMA showed elevated levels of anxiety-like behaviour in the emergence and social interaction tests, respectively. At 9 weeks post-MDMA, the rats displayed an increase in anxiety on the elevated plus-maze test relative to controls. Ten weeks following treatment the rats were killed and their brains dissected and neurotramitter content analysed using High Performance Liquid Chromotography (HPLC). Rats previously given MDMA showed significantly decreased 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in the amygdala, hippocampus and striatum relative to controls. This 5-HT depletion may have a causal role in producing increased anxiety-like behaviours in MDMA-treated rats. These results are consistent with human studies suggesting that exposure to high doses of MDMA may predispose to long-term psychological problems such as anxiety and depression.
Insights
Long-term 3,4-methlyenedioxymethampthetamine (MDMA, "Ecstasy") exposure in rats led to increased anxiety-like behaviors. This was associated with significant reductions in serotonin (5-HT) and its metabolite (5-HIAA) in key brain regions.
Area of Science:
- Neuroscience
- Toxicology
- Behavioral Science
Background:
- 3,4-methlyenedioxymethampthetamine (MDMA, "Ecstasy") is a recreational drug with known acute effects.
- The long-term neurotoxic and behavioral consequences of MDMA exposure require further investigation.
Purpose of the Study:
- To investigate the long-term behavioral and neurotoxic effects of MDMA in a rat model.
- To examine the relationship between MDMA-induced neurochemical changes and anxiety-like behaviors.
Main Methods:
- Rats received MDMA (5 mg/kg) or vehicle injections over two consecutive days at 28°C.
- Behavioral assessments (emergence, social interaction, elevated plus-maze) were conducted at 4, 6, and 9 weeks post-treatment.
- Neurotransmitter levels (5-HT, 5-HIAA) in brain regions (amygdala, hippocampus, striatum) were analyzed via HPLC at 10 weeks.
Main Results:
- MDMA administration caused acute hyperthermia and hyperactivity.
- Rats treated with MDMA exhibited significantly increased anxiety-like behaviors from 4 to 9 weeks post-treatment.
- Significant reductions in 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were observed in the amygdala, hippocampus, and striatum of MDMA-treated rats.
Conclusions:
- MDMA exposure can lead to persistent anxiety-like behaviors in rats.
- The observed decrease in 5-HT and 5-HIAA levels may underlie the long-term anxiety induced by MDMA.
- Findings align with human studies suggesting MDMA predisposes to long-term psychological issues like anxiety and depression.