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Correlating brain metabolism with stereotypic and locomotor behavior
Susan M Melnick1, Diana L Dow-Edwards
1State University of New York Downstate Medical Center, Brooklyn, New York 11203, USA.
Behavior Research Methods, Instruments, & Computers : a Journal of the Psychonomic Society, Inc
|November 1, 2003
Summary
Developmental cocaine exposure alters dopamine system function. This study found that cocaine-induced changes enhance the link between brain metabolism and behavior under drug challenge, potentially due to lost inhibitory control.
Area of Science:
- Neuroscience
- Developmental Biology
- Pharmacology
Background:
- Developmental exposure to cocaine is known to disrupt brain function and behavior.
- Understanding the neurobiological underpinnings of these alterations is crucial for addressing long-term consequences.
Purpose of the Study:
- To investigate the relationship between brain glucose metabolism and behavioral responses to a dopamine agonist challenge in rats with developmental cocaine exposure.
- To determine if early-life cocaine exposure alters the correlation between metabolic activity in dopamine circuits and behavioral output.
Main Methods:
- Rats exposed to cocaine (50 mg/kg/day) or saline during the preweaning period were challenged with SKF 82958 (a D1 dopamine agonist) or saline at 60 days of age.
- Cerebral glucose metabolism was measured using deoxyglucose during peak behavioral responses (locomotor and stereotypic activity).
- Pearson correlations were analyzed between behavioral measures and glucose metabolism rates in the nigrostriatal and mesolimbic dopamine systems.
Main Results:
- In control rats, mesolimbic metabolism correlated with locomotor activity under saline conditions.
- These correlations were absent in cocaine-exposed rats under saline conditions.
- Following SKF 82958 challenge, controls showed no correlation between behavior and metabolism in these circuits, whereas cocaine-exposed rats exhibited positive correlations, indicating enhanced coupling.
Conclusions:
- Developmental cocaine exposure strengthens the coupling between mesolimbic and nigrostriatal dopamine system metabolism and behavioral output during drug challenge.
- This enhanced coupling may result from a loss of inhibitory influences within these dopamine systems.
- Correlating behavior with cerebral glucose metabolism offers a novel approach to studying the effects of developmental cocaine exposure on brain function.