Effects of long-term episodic access to ethanol on the expression of an alcohol deprivation effect in low alcohol-consuming rats.
BACKGROUND
The alcohol-preferring (P) and -nonpreferring (NP) and high alcohol-drinking (HAD) and low alcohol-drinking (LAD) rats have been selectively bred for divergent preference for ethanol over water. In addition, both P and HAD rats display an alcohol deprivation effect (ADE). This study was undertaken to test whether the NP, LAD-1, and LAD-2 lines of rats could display an ADE as well.


METHODS
Adult female NP, LAD-1, and LAD-2 rats were given concurrent access to multiple concentrations of ethanol [5, 10, 15% (v/v)] and water in an ADE paradigm involving an initial 6 weeks of 24-hr access to ethanol, followed by four cycles of 2 weeks of deprivation from and 2 weeks of re-exposure to ethanol (5, 10, and 15%). A control group had continuous access to the ethanol concentrations (5, 10, and 15%) and water through the end of the fourth re-exposure period.


RESULTS
For NP rats, a preference for the highest ethanol concentration (15%) was evident by the end of the fifth week of access (approximately 60% of total ethanol fluid intake). Contrarily, LAD rats did not display a marked preference for any one concentration of ethanol. All three lines displayed an ADE after repeated cycles of re-exposure to ethanol, with the general ranking of intake being LAD-1 > NP > LAD-2 (e.g., for the first day of reinstatement of the third re-exposure cycle, intakes were 6.5, 2.9, and 2.4 g/kg/day compared with baseline values of 3.1, 2.0, and 1.3 g/kg/day for each line, respectively). By the 13th week, rats from all three lines, with a ranking of LAD-1 > NP > LAD-2, were drinking more ethanol (3.3, 2.2, and 2.0 g/kg/day, respectively) compared with their consumption during the first week of access (approximately 1.1 g/kg/day for all three lines).


CONCLUSIONS
These data indicate that access to multiple concentrations of ethanol and exposure to multiple deprivation cycles can partially overcome a genetic predisposition of NP, LAD-1, and LAD-2 rats for low alcohol consumption. In addition, the findings suggest that genetic control of low alcohol consumption in rats is not associated with the inability to display an ADE.
Bell
Richard L
RL
Indiana University School of Medicine, Department of Psychiatry, Institute of Psychiatric Research, 791 Union Drive, Indianapolis, IN 46202-4887, USA. ribell@iupui.edu
Rodd
Zachary A
ZA
Boutwell
Caron L
CL
Hsu
Cathleen C
CC
Lumeng
Lawrence
L
Murphy
James M
JM
Li
Ting-Kai
TK
McBride
William J
WJ
D000428:Alcohol Drinking / Q000235:genetics*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000008:administration & dosage*; D005260:Female; D051381:Rats; D013045:Species Specificity; D013995:Time; D013997:Time Factors
D000431:Ethanol