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Microdialysis of Ethanol During Operant Ethanol Self-administration and Ethanol Determination by Gas Chromatography
Published on: September 5, 2012
In vivo time-course changes in ethanol levels sampled with subcutaneous microdialysis
Eric A Engleman1, Cynthia M Ingraham, Kelle M Franklin
1Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN 46220, USA. eenglema@iupui.edu
Alcoholism, Clinical and Experimental Research
|January 25, 2008
Summary
Subcutaneous microdialysis effectively monitors ethanol (EtOH) levels in rats, mirroring blood concentrations. This novel technique allows detailed analysis of EtOH changes during drinking behaviors.
Area of Science:
- Pharmacology
- Neuroscience
- Animal Models
Background:
- Investigating in vivo ethanol (EtOH) concentrations requires precise measurement techniques.
- Subcutaneous (s.c.) microdialysis offers a potential novel method for sampling EtOH levels.
- Previous methods may not provide detailed time-course data during consumption.
Purpose of the Study:
- To evaluate time-course changes in in vivo EtOH concentrations using s.c. microdialysis.
- To test the hypothesis that s.c. EtOH levels reflect blood EtOH concentrations.
- To establish s.c. microdialysis as a tool for studying EtOH consumption patterns.
Main Methods:
- Designed and characterized a novel loop-style microdialysis probe for s.c. implantation in Wistar and alcohol-preferring rats.
- Determined in vivo probe extraction fraction using the alcohol clamp and no-net-flux (NNF) methods.
- Administered EtOH systemically (i.p.) and orally (i.g.) to assess dose-response, time-course, and compare s.c. dialysate with arterial blood EtOH levels.
Main Results:
- In vivo probe recovery was 69%, comparable to in vitro recovery (73%).
- EtOH administration (0.5-2.0 g/kg) resulted in dose-dependent increases in s.c. dialysate EtOH, peaking within 15 minutes.
- S.c. microdialysis EtOH levels closely mirrored arterial blood EtOH concentrations following systemic administration.
- During a 1-hour drinking session, s.c. EtOH levels in alcohol-preferring rats peaked around 50 mg%.
Conclusions:
- Subcutaneous EtOH concentrations measured by microdialysis exhibit a similar time course to blood EtOH levels.
- S.c. microdialysis is a viable and informative technique for detailed analysis of EtOH pharmacokinetics.
- This method facilitates the study of EtOH dynamics during active consumption in animal models.
