Conditioned aversion to an intraperitoneally injected odor CS in rats]

Two experiments were conducted to specify an CS property of intraperitoneally injected odor substance in conditioned odor aversion formation. In experiment 1, three groups of water-restricted rats received one trial of conditioning with intraperitoneal injections of orange-extract (CS) and LiCl(UCS). The CS-UCS intervals of experimental groups were 30 minutes (Group IE-30) and 120 minutes (Group IE-120). In the test trial, Group IE-30 rats showed aversion to the test solution (0.5% orange extract), whereas no significant difference was observed between the control group and Group IE-120. In experiment 2, three groups of rats received one or two or three conditioning trials (Groups E1, E2 and E3, respectively). The CS-UCS interval of all groups was 30 minutes. In the test trial, rats in Groups E2 and E3 consumed less amount of test solution (0.5% orange extract) than the control rats, whereas no significant difference was observed between Group E1 and the control group. These results suggest that the intraperitoneally injected odor substance have CS property on conditioned odor aversion.