Self-administered ethanol as a discriminative stimulus in rats

Area of Science:

• Neuroscience
• Behavioral Pharmacology

Background:

• Drug administration methods (self- vs. experimenter-administered) influence neurochemical and behavioral outcomes.
• Orally self-administered drugs, like ethanol, possess unique peripheral stimulus effects absent in experimenter-administered routes.

Purpose of the Study:

• To investigate if orally self-administered (SA) ethanol functions as a discriminative stimulus.
• To ascertain the role of peripheral ethanol effects in its discriminative stimulus properties.

Main Methods:

• Twelve Long-Evans rats were trained to orally self-administer ethanol (750 mg/kg) and discriminate it from water.
• Substitution tests were conducted using various doses of orally SA and intraperitoneally (IP) administered ethanol.

Main Results:

• Six out of twelve rats successfully discriminated orally SA ethanol from water.
• Both orally SA and IP administered ethanol substituted for the training dose, with no significant difference in ED(50) values.
• Lower doses of IP ethanol did not substitute, suggesting central nervous system mediation of SA ethanol's discriminative effects.

Conclusions:

• Orally self-administered ethanol effectively serves as a discriminative stimulus in rats.
• The discriminative stimulus properties of orally SA ethanol are predominantly mediated by central nervous system (CNS) effects, not peripheral ones.