Controlled and behaviorally relevant levels of oral ethanol intake in rhesus macaques using a flavorant-fade procedure.
BACKGROUND
Flavorant-fading procedures can initiate and maintain oral ethanol intake in rodents. The present study developed a similar procedure to achieve controlled and behaviorally relevant levels of ethanol intake in monkeys.


METHODS
Male rhesus macaques (N = 13) were initially given the opportunity to consume 0.5 g/kg of a 1% (w/v) ethanol plus 4% (w/v) Tang solution in 1-hr limited-access sessions without the requirement of an operant response. Once consumption was stable at a particular concentration (%) and/or amount (g/kg), animals were given access to higher concentrations and/or amounts of ethanol. Animals were tested on a bimanual motor skill (BMS) task 20 and 90 min after consumption to assess behavioral impairment. Blood alcohol levels (BALs) were assessed after a session in which animals had the opportunity to consume up to 3.0 g/kg of 6% (w/v) ethanol.


RESULTS
The gradual fading up of higher concentrations and amounts of ethanol resulted in controlled and robust levels (>2.0 g/kg) of ethanol intake in half of the subjects. Increasing the concentration of the sweetener from 4 to 6% (w/v) was effective in initiating consumption in three animals. Two monkeys required the additional step of presenting the increased-sweetener solutions after a meal (postprandial consumption) to initiate significant ethanol intake. Animals were significantly impaired on the BMS task after consumption of 2.0, 2.5, and 3.0 g/kg of ethanol. Individual consumption ranging from 0.8 to 3.0 g/kg of ethanol produced BALs of 18 to 269 mg/dl.


CONCLUSIONS
The flavorant-fading procedure was effective in producing behaviorally relevant levels of ethanol consumption in rhesus macaques. This model facilitated a randomized-dose procedure to determine the behavioral effects of 0.5 to 3.0 g/kg of ethanol. This procedure therefore is of significant utility in determining behavioral or physiologic effects of specific doses of consumed ethanol in monkeys.
Katner
Simon N
SN
Department of Neuropharmacology, The Scripps Research Institute, La Jolla, California 92037, USA. skatner@scripps.edu
Flynn
Claudia T
CT
Von Huben
Stefani N
SN
Kirsten
Amber J
AJ
Davis
Sophia A
SA
Lay
Christopher C
CC
Cole
Maury
M
Roberts
Amanda J
AJ
Fox
Howard S
HS
Taffe
Michael A
MA
D000284:Administration, Oral; D000428:Alcohol Drinking / Q000523:psychology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000008:administration & dosage*; D005421:Flavoring Agents / Q000008:administration & dosage*; D008253:Macaca mulatta; D008297:Male; D012055:Reinforcement Schedule; D012646:Self Administration
D005421:Flavoring Agents; D000431:Ethanol