Failure to establish a conditioned place preference with ethanol in rats

Area of Science:

• Neuroscience
• Pharmacology
• Behavioral Science

Background:

• Drugs of abuse often induce conditioned place preference in rats.
• Ethanol is a widely consumed substance with abuse potential.

Purpose of the Study:

• To investigate if ethanol, across various doses, can establish a conditioned place preference in rats.
• To compare ethanol's effects with amphetamine in a conditioned place preference paradigm.

Main Methods:

• Rats received intraperitoneal injections of ethanol (50–1000 mg/kg) or amphetamine (2 mg/kg).
• Conditioned place preference/aversion was assessed by comparing time spent in drug-paired versus neutral environments.
• Intravenous ethanol administration (1, 2, or 8 mg/kg) via jugular cannulae was also tested.
• Blood and brain ethanol levels were measured after intravenous administration.

Main Results:

• Ethanol administration via intraperitoneal injection did not produce conditioned place preference or aversion.
• Amphetamine (2 mg/kg) successfully induced a conditioned place preference, independent of hyperactivity.
• Intravenous ethanol, even at doses supporting self-administration, failed to yield conditioned place preference.
• Measured ethanol levels in blood and brain were very low following intravenous administration.

Conclusions:

• Rats do not appear to self-administer ethanol primarily for its intoxicating effects.
• The affective state induced by ethanol administration is not readily associated with environmental cues.
• Ethanol's reinforcing properties may stem from mechanisms other than direct intoxication-induced conditioning.