Backward conditioning of tumor necrosis factor-alpha in a single trial

Abstract

The current study examined the effect of backward conditioning with three different time intervals between exposures to lipopolysaccharide (LPS) as the unconditioned stimulus (US) and saccharin taste in water as the potential conditioned stimulus (CS). Forty-eight naive female BALB/c mice at three months of age served as subjects, divided into six groups. Four groups were assigned to Experiment 1 for the tumor necrosis factor alpha (TNF-alpha) measure, and the remaining two groups were used in Experiment 2 to measure taste aversion behavior. Both experiments employed a single trial. The timing of introduction to the saccharin taste varied between 3 min, 7 h, and 24 h following an LPS injection in Experiment 1. Experiment 2 employed the three-minute interval only. These intervals correspond to distinct immunological, physiological, and behavioral events induced by LPS. On the day after re-exposure to the saccharin taste, the TNF-alpha groups were challenged with LPS to test the LPS tolerance response. While backward conditioning of taste aversion behavior was not observed, some evidence of conditioned TNF-alpha response and subsequent development of LPS tolerance was observed with backward conditioning in a single trial. This exploratory study demonstrated that the effect of backward conditioning on conditioned TNF-alpha response and LPS tolerance response in a single trial depended on the timing of when a CS is presented after LPS exposure. Published by Elsevier Inc.