Effects of a repeated low dose of LiCl injection under conditioned taste/flavor aversion using xylene

Abstract

We examined whether repeated injections with low-doses lithium chloride (LiCl) as unconditioned stimulus (US) established conditioning as applied conditioned taste aversion (CTA) experiment, using xylene solution as a conditioned stimulus (CS). In the conditioning procedure, water-deprived male rats were exposed to xylene solution for 30 min, followed by LiCl or saline injection. As a two-bottle test, xylene solution and usual drink water were simultaneously provided to rats on the next day of the conditioning and measured each consumption volume. Conditioning and two-bottle test were repeated eight times respectively by turns. Groups of no treatment and sham injection after xylene ingestion were added to verify the effects of external contexts on establishment of CTA. Results indicate that the CTA was gradually established when the US was repeatedly presented even if the US was very low concentration, and the organic solvent functioned as CS even if it was not so desirable for animals. External contexts, such as handling and the ‘pain’ induced by injection, did not affect the establishment of the CTA in the present study. Although xylene was used as solution in the present study and defined as flavor stimulus, gas should be used to examine the effects of odor stimulus.