Initiation of Ethanol Reinforcement using a Sucrose‐Substitution Procedure in Food‐ and Water‐Sated Rats

TLDR

Ethanol preference in rats can be modified by operant conditioning, and existing methods often require food or fluid deprivation. The study hypothesizes that mechanisms regulating intravascular and intragastric ethanol self‑administration also operate during oral self‑administration. Rats were trained to lever‑press for a 20 % sucrose solution, then low ethanol concentrations were added while sucrose was gradually reduced over 25 sessions until a 10 % ethanol solution without sucrose was presented. The procedure enabled rats to maintain responding for ethanol up to 40.

Abstract

Rats, maintained on free access to both food and water, were trained to press a lever to obtain a 20% sucrose solution. When presentation of the sucrose solution was maintaining responding, low ethanol concentrations were added to the solution. Over 25 sessions, the solution presented as reinforcement was gradually reduced in sucrose concentration until a 10% ethanol solution with no sucrose was presented. Following this initiation procedure, ethanol concentrations up to and including 40% ethanol were found to maintain responding. At the higher ethanol concentrations, the rats consumed doses of ethanol between 0.90 and 0.95 g/kg in the 30‐min session. When a concurrent choice between ethanol and water was available in the operant chamber, the rats responded on the lever associated with 10% ethanol presentation. Home cage preference between ethanol and water was found to be altered following the operant ethanol experience with the rats acceptability for 10% ethanol increased prior to the start of the experiment This initiation procedure provides another manner in which ethanol reinforcement can be instigated in animals that have not been either food‐ or fluid‐deprived. It is hypothesized that mechanisms which may regulate the intravascular and intragastric self‐administration of ethanol may also be operating when the oral route is employed.