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 beta-endorphin, met-enkephalin, and dynorphin A(1-8,) 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 beta-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 beta-endorphin. A late increase in the dialysate content of dynorphin A(1-8) 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 beta-endorphin release at the level of midbrain/VTA may influence alcohol reinforcement.
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 beta-endorphin, met-enkephalin, and dynorphin A(1-8,) 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 beta-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 beta-endorphin. A late increase in the dialysate content of dynorphin A(1-8) 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 beta-endorphin release at the level of midbrain/VTA may influence alcohol reinforcement.
Authors: Yuki Moriya; Yoshiyuki Kasahara; F Scott Hall; Yasufumi Sakakibara; George R Uhl; Hiroaki Tomita; Ichiro Sora Journal: Psychopharmacology (Berl) Date: 2014-11-04 Impact factor: 4.530
Authors: Irene Morganstern; Guo-Q Chang; Jessica R Barson; Zhiyu Ye; Olga Karatayev; Sarah F Leibowitz Journal: Alcohol Clin Exp Res Date: 2010-03-10 Impact factor: 3.455
Authors: Jessica R Barson; Ambrose J Carr; Jennifer E Soun; Nasim C Sobhani; Pedro Rada; Sarah F Leibowitz; Bartley G Hoebel Journal: Alcohol Clin Exp Res Date: 2009-11-24 Impact factor: 3.455