Intermittent access to 20% ethanol induces high ethanol consumption in Long-Evans and Wistar rats.
BACKGROUND
There has been some difficulty getting standard laboratory rats to voluntarily consume large amounts of ethanol without the use of initiation procedures. It has previously been shown that standard laboratory rats will voluntarily consume high levels of ethanol if given intermittent-access to 20% ethanol in a 2-bottle-choice setting [Wise, Psychopharmacologia 29 (1973), 203]. In this study, we have further characterized this drinking model.


METHODS
Ethanol-naïve Long-Evans rats were given intermittent-access to 20% ethanol (three 24-hour sessions per week). No sucrose fading was needed and water was always available ad libitum. Ethanol consumption, preference, and long-term drinking behaviors were investigated. Furthermore, to pharmacologically validate the intermittent-access 20% ethanol drinking paradigm, the efficacy of acamprosate and naltrexone in decreasing ethanol consumption were compared with those of groups given continuous-access to 10 or 20% ethanol, respectively. Additionally, ethanol consumption was investigated in Wistar and out-bred alcohol preferring (P) rats following intermittent-access to 20% ethanol.


RESULTS
The intermittent-access 20% ethanol 2-bottle-choice drinking paradigm led standard laboratory rats to escalate their ethanol intake over the first 5 to 6 drinking sessions, reaching stable baseline consumption of high amounts of ethanol (Long-Evans: 5.1 +/- 0.6; Wistar: 5.8 +/- 0.8 g/kg/24 h, respectively). Furthermore, the cycles of excessive drinking and abstinence led to an increase in ethanol preference and increased efficacy of both acamprosate and naltrexone in Long-Evans rats. P-rats initiate drinking at a higher level than both Long-Evans and Wistar rats using the intermittent-access 20% ethanol paradigm and showed a trend toward a further escalation in ethanol intake over time (mean ethanol intake: 6.3 +/- 0.8 g/kg/24 h).


CONCLUSIONS
Standard laboratory rats will voluntarily consume ethanol using the intermittent-access 20% ethanol drinking paradigm without the use of any initiation procedures. This model promises to be a valuable tool in the alcohol research field.
Simms
Jeffrey A
JA
Ernest Gallo Clinic and Research Center, University of California San Francisco, Emeryville, California 94608, USA.
Steensland
Pia
P
Medina
Brian
B
Abernathy
Kenneth E
KE
Chandler
L Judson
LJ
Wise
Roy
R
Bartlett
Selena E
SE
D000077443:Acamprosate; D000427:Alcohol Deterrents / Q000627:therapeutic use; D000428:Alcohol Drinking / Q000188:drug therapy; D000818:Animals; D000431:Ethanol / Q000008:administration & dosage* / Q000097:blood; D008297:Male; D023421:Models, Animal; D009271:Naltrexone / Q000627:therapeutic use; D009292:Narcotic Antagonists / Q000627:therapeutic use; D051381:Rats; D020318:Rats, Long-Evans; D017208:Rats, Wistar; D013654:Taurine / Q000031:analogs & derivatives / Q000627:therapeutic use; D013997:Time Factors
D000427:Alcohol Deterrents; D009292:Narcotic Antagonists; D013654:Taurine; D000431:Ethanol; D009271:Naltrexone; D000077443:Acamprosate