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Cocaine increases 5-HT1B mRNA in rat nucleus accumbens shell neurons
B J Hoplight1, E S Vincow, J F Neumaier
1Departments of Psychiatry and Behavioral Sciences, Harborview Medical Center, University of Washington, Box 359911, 325 Ninth Avenue, Seattle, WA 98104-2499, USA.
Neuropharmacology
|October 25, 2006
Summary
Chronic cocaine exposure increases serotonin 5-HT(1B) receptor mRNA in rat brains, particularly in areas linked to addiction. Social stress may also upregulate these receptors, potentially influencing relapse risk.
Area of Science:
- Neuroscience
- Pharmacology
- Molecular Biology
Background:
- Serotonin 5-HT(1B) receptors are known to influence behavioral responses to cocaine.
- The impact of cocaine on endogenous 5-HT(1B) receptor expression remains largely uncharacterized.
Purpose of the Study:
- To investigate the effects of binge cocaine administration on 5-HT(1B) mRNA expression in the rat brain.
- To explore potential roles of social stress in modulating 5-HT(1B) mRNA levels.
Main Methods:
- Rats were subjected to acute or chronic binge cocaine administration.
- 5-HT(1B) mRNA expression levels were quantified in specific brain regions, including the nucleus accumbens shell and dorsal striatum.
- Control groups received vehicle treatments, with some animals housed with cocaine-treated subjects to assess social stress effects.
Main Results:
- Chronic, but not acute, binge cocaine exposure significantly increased 5-HT(1B) mRNA expression by approximately 80% in the nucleus accumbens shell and dorsal striatum.
- Chronic vehicle treatment also led to increased 5-HT(1B) mRNA in the nucleus accumbens shell, but this was attributed to social housing with cocaine-treated animals.
- These findings suggest that repeated cocaine exposure and social stress can upregulate 5-HT(1B) mRNA.
Conclusions:
- Repeated exposure to cocaine upregulates serotonin 5-HT(1B) mRNA in key brain regions involved in reward and addiction.
- Social stress, potentially through housing conditions, may also contribute to the upregulation of 5-HT(1B) mRNA.
- Both cocaine exposure and social stress are relevant factors implicated in the risk for cocaine addiction relapse.
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