Short-term cocaine self administration alters striatal gene expression

Area of Science:

• Neuroscience
• Molecular Biology
• Pharmacology

Background:

• Cocaine addiction is a significant public health issue.
• Understanding the molecular mechanisms underlying cocaine's effects on the brain is crucial for developing effective treatments.
• Gene expression changes in the dorsal striatum are implicated in the neuroadaptations associated with drug seeking behavior.

Purpose of the Study:

• To investigate the effects of short-term cocaine self-administration on the expression of specific mRNAs in the rat dorsal striatum.
• To determine if cocaine self-administration differentially regulates the expression of preprodynorphin, preproenkephalin, c-fos, and zif/268 mRNAs.

Main Methods:

• Rats underwent daily cocaine or saline self-administration sessions.
• Quantitative in situ hybridization was used to measure mRNA levels in the dorsal striatum.
• Tissue was collected 1 hour after the final self-administration session.

Main Results:

• Cocaine self-administration significantly increased preprodynorphin mRNA levels in a patchy distribution within the dorsal striatum.
• No significant changes were observed in preproenkephalin, c-fos, or zif/268 mRNA levels following cocaine self-administration.
• These findings indicate a selective regulation of preprodynorphin gene expression.

Conclusions:

• Short-term cocaine self-administration selectively upregulates preprodynorphin mRNA in the dorsal striatum.
• The regulation of preprodynorphin gene expression is dissociable from that of immediate early genes (c-fos, zif/268) and preproenkephalin mRNA.
• These results contribute to understanding the distinct molecular pathways involved in the early stages of cocaine use.