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Serotonin laterality in amygdala predicts performance in the elevated plus maze in rats
1McLean Hospital, Belmont, MA 02178, USA.
Neuroreport
|January 5, 2000
Summary
Anxiety in rats is linked to specific brain chemical imbalances. Increased serotonin in the right amygdala and dopamine in the right prefrontal cortex correlate with higher anxiety levels.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Neurochemistry
Background:
- Hemispheric asymmetries in neurotransmitter levels are increasingly recognized as potential contributors to behavioral variations.
- The elevated plus maze is a standard tool for assessing anxiety-like behaviors in rodents.
- Understanding the neurochemical underpinnings of anxiety is crucial for developing targeted therapeutic strategies.
Purpose of the Study:
- To investigate the correlation between hemispheric neurotransmitter asymmetries and anxiety-related behavior in adult rats.
- To determine if specific neurotransmitters in limbic brain regions are lateralized in anxious rats.
Main Methods:
- Adult rats were behaviorally assessed using the elevated plus maze.
- Neurotransmitter content in limbic brain regions (amygdala, prefrontal cortex, accumbens, hippocampus, striatum) was quantified using High-Performance Liquid Chromatography with Electrochemical Detection (HPLC-EC).
- Correlational analyses were performed between behavioral measures and regional neurotransmitter lateralization.
Main Results:
- A significant positive correlation was found between increased anxiety (spending more time in the closed arm) and serotonin lateralization in the amygdala (r=0.86, p < 0.003).
- Specifically, greater serotonin levels in the right amygdala compared to the left were associated with increased anxiety.
- Increased dopamine in the right prefrontal cortex also showed a strong correlation with anxiety (r=0.84, p < 0.01).
- No significant correlations were observed in the accumbens, hippocampus, or striatum.
Conclusions:
- These findings support the hypothesis that the right hemisphere plays a role in emotional processing, specifically anxiety.
- Right-sided amygdala serotonin lateralization is implicated in heightened anxiety.
- Cortical dopamine lateralization may be associated with attentional processes directed towards the environment during anxious states.