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Ventral Tegmental Microinjections of Quinpirole Decrease Ethanol and Sucrose‐Reinforced Responding
Author(s) -
Hodge Clyde W.,
Haraguchi Miki,
Erickson Heidi,
Samson Herman H.
Publication year - 1993
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.1993.tb00778.x
Subject(s) - quinpirole , ventral tegmental area , microinjections , dopamine , ethanol , endocrinology , medicine , saccharin , agonist , reinforcement , psychology , chemistry , anesthesia , dopamine receptor , dopaminergic , microinjection , biochemistry , receptor , social psychology
The effects of microinjections in the ventral tegmental area (VTA) of the dopamine D2/D3 agonist quinpirole on ethanol‐ and sucrosereinforced responding were tested. Two groups of Long‐Evans rats were trained to lever press on a fixed‐ratio 4 schedule with 10% ethanol (v/v) ( n = 8) and 75% sucrose (w/v) ( n = 10) presented as the reinforcer. Weekly bilateral injections of quinpirole were tested in the ethanol group (0.0, 0.001, 0.01, 0.1, and 1.0 μg/μl) and sucrose group (0.0, 0.01, 0.1, 1.0, and 10.0 μg/μl). Quinpirole dose dependently decreased ethanol‐ and sucrose‐reinforced responding, but the dose‐effect curve for sucrose was shifted two orders of magnitude to the right of the ethanol curve. Temporal response patterns during control sessions for both reinforcers were characterized by initial high rates that terminated after approximately 10 min. VTA injections of quinpirole dose dependently delayed the onset of the first response and the initial high rate period, and resulted in an early termination of responding following onset. These data support the hypothesis that dopamine activity in the VTA is involved in the regulation of ethanol‐reinforced responding in a manner similar to that of other reinforcers.