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Activity-wheel stress and serotonergic hypersensitivity in rats
A R Mayeda1, J R Simon, J N Hingtgen
1Department of Psychiatry, Indiana University School of Medicine, Indianapolis.
Pharmacology, Biochemistry, and Behavior
|June 1, 1989
Summary
Stress significantly alters brain chemistry in rats. Activity wheel stress reduced serotonin metabolite levels and increased serotonin receptor sensitivity in the frontal cortex, indicating a neurochemical response to stress.
Area of Science:
- Neuroscience
- Biochemistry
- Animal Behavior
Background:
- Stress impacts neurochemistry and behavior.
- Serotonin system is implicated in stress response.
- Activity wheel models can induce behavioral and physiological changes.
Purpose of the Study:
- To investigate the neurochemical effects of activity wheel stress on the serotonin system in rats.
- To examine changes in serotonin metabolite levels and serotonin receptor binding.
- To explore the relationship between stress-induced behavior and central serotonin receptor sensitivity.
Main Methods:
- Adult male Wistar rats were subjected to activity wheel stress.
- Control rats were pair-housed and pair-fed.
- Rats were trained on a variable interval schedule for milk reinforcement.
- Biochemical analysis of frontal cortical homogenates was performed after behavioral changes were observed.
Main Results:
- A 50% decrease in the serotonin metabolite 5-hydroxyindoleacetic acid was observed in stressed rats.
- An increase of 19% in Bmax for ketanserin binding (a measure of serotonin receptor availability) was found in stressed rats.
- These biochemical changes correlated with specific behavioral patterns during the stress paradigm.
Conclusions:
- Activity wheel stress leads to significant alterations in the central serotonin system.
- Stress appears to increase the sensitivity of central serotonin receptors.
- These findings contribute to understanding the neurobiological underpinnings of stress responses.