Effect of Acute Ethanol Administration on the Release of Opioid Peptides From the Midbrain Including the Ventral Tegmental Area
Article first published online: 19 MAR 2009
Copyright © 2009 by the Research Society on Alcoholism
Alcoholism: Clinical and Experimental Research
Volume 33, Issue 6, pages 1033–1043, June 2009
How to Cite
Jarjour, S., Bai, L. and Gianoulakis, C. (2009), Effect of Acute Ethanol Administration on the Release of Opioid Peptides From the Midbrain Including the Ventral Tegmental Area. Alcoholism: Clinical and Experimental Research, 33: 1033–1043. doi: 10.1111/j.1530-0277.2009.00924.x
- Issue published online: 20 MAY 2009
- Article first published online: 19 MAR 2009
- Received for publication September 17, 2008; accepted January 23, 2008.
- Dynorphin A1–8;
- In Vivo Microdialysis
Background: Experimental evidence suggests that ethanol alters the activity of the endogenous opioid peptide systems in a dose and brain-region dependent manner. These alterations may influence the processes of ethanol reward and reinforcement. Thus, it was the objective of this study to investigate the response of the 3 major opioid peptide systems (endorphins, enkephalins, and dynorphins) to acute ethanol administration, at the level of the midbrain including the ventral tegmental area (midbrain/VTA), a region important for drug, including ethanol reinforcement.
Methods: Using the in vivo microdialysis technique coupled with specific solid-phase radioimmunoassay for β-endorphin, met-enkephalin, and dynorphin A1–8, changes in the extracellular concentration of theses peptides at the level of midbrain/VTA were determined at distinct time points following the administration of 0.0 (saline), 0.8, 1.2, 1.6, 2.0, and 2.4 g ethanol/kg B.Wt.
Results: A biphasic effect of ethanol on β-endorphin release was found, with low to medium (1.2, 1.6, and 2.0 g) but not high (2.4 g) doses of ethanol, inducing a significant increase in the dialysate content of β-endorphin. A late increase in the dialysate content of dynorphin A1–8 was observed in response to the 1.2 g ethanol dose. However, none of the ethanol doses tested significantly altered the content of met-enkephalin in the dialysate.
Conclusions: The present findings suggest that the ethanol-induced increase of β-endorphin release at the level of midbrain/VTA may influence alcohol reinforcement.