A 3-day exposure to 10% ethanol with 10% sucrose successfully initiates ethanol self-administration.
The initiation phase of ethanol self-administration is difficult to study using the well-established, sucrose-fading procedure due to the changing concentrations of ethanol in the first few days. The purpose of this experiment was to test whether a modified sucrose-substitution procedure in which rats are initially exposed to high concentrations of ethanol and sucrose for three days would successfully initiate ethanol self-administration. Male Long-Evans rats were trained to lever-press with a 10% sucrose solution in which four or 20 responses allowed 20-min access to the solution. Subsequently, rats were exposed to a 3-day period of operant self-administration of 10% sucrose+10% ethanol. This constant-concentration exposure was followed by the standard procedure in which sucrose is completely faded out. The establishment of ethanol self-administration was determined by ethanol intake, pre- and postprocedure two-bottle choice preference tests, and extinction trials. The mean ethanol intake was 2.2 times higher on day 2 compared with day 1 on the 10% sucrose+10% ethanol solution. After fading out the sucrose, the daily intake of 10% ethanol solution over 5 days was stable at approximately 0.57 g/kg. Ethanol preference was approximately threefold higher after the modified sucrose-fading procedure. Responding during a single session extinction test was dramatically increased from 4 to 61+/-13 or 20 to 112+/-22 responses in 20 min. Similar to the standard sucrose-fading method, we did not observe a significant relationship between extinction responding and ethanol intake. Blood alcohol concentrations were 4.5 mM 20 min after consumption began. We conclude that initiation and establishment of ethanol self-administration will occur using this modified sucrose-fading procedure.
Carrillo
Jennifer
J
College of Pharmacy, Department of Pharmacology, The University of Texas at Austin, Austin, TX 78712, USA.
Howard
Elaina C
EC
Moten
Misbah
M
Houck
Brenda D
BD
Czachowski
Cristine L
CL
Gonzales
Rueben A
RA
D000428:Alcohol Drinking / Q000523:psychology*; D000818:Animals; D002492:Central Nervous System Depressants / Q000097:blood / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects; D004327:Drinking Behavior / Q000187:drug effects; D000431:Ethanol / Q000097:blood / Q000494:pharmacology*; D005108:Extinction, Psychological; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans; D012646:Self Administration; D013395:Sucrose / Q000494:pharmacology*
D002492:Central Nervous System Depressants; D000431:Ethanol; D013395:Sucrose