7. Chronic, inescapable and contiguity foot-shocks to feeding period modifies eating behavior in rats
Marina Liliana González-Torres-Department of psychology, Autonomous University of Aguascalientes, Aguascalientes, Aguascalientes, Mexico, Cristiano Valerio dos Santos-Research and Studies on Behavior Center, University of Guadalajara, Guadalajara, Jalisco, Mexico.
This study aimed to evaluate the differential effects of chronic middle inescapable shocks on feeding behavior applied before or after the feeding period, as well as the period of the light-dark cycle. Besides, in the first experiment investigated whether the possibility of escape from shocks differentially affects the food intake and the body weight gain in rats. In Experiment 1, we exposed two groups of rats to escape foot-shocks after baseline condition; if before or after food access in the dark period, the other two groups were yoked to the first, and a control group did not exposure to shocks. In the second experiment, inescapable shocks or no shocks occurred after or before to food access in the light period after the baseline condition in three groups of rats. Results suggest that chronic stress induced by electric shocks decrease food intake and body weight gain, especially with inescapable shocks, and when it occurred before food access, regardless of the time in which the electric shocks were administered. The findings support the link between uncontrollable and chronic stress and eating behavior, and they reveal the importance of contiguity of the stressor and the feeding period. Keywords: inescapable stressor, chronic stress, learned helplessness, food intake, contiguity to feeding period, rats..
8. Absence of latent inhibition in food aversion conditioning in Japanese fire-bellied newts
Weisheng Zhao-Kanazawa University, Tohru Taniuchi-Kanazawa University
The present study examined latent inhibition (CS preexposure effect) in food aversion conditioning in Japanese fire-bellied newts. Newts in Preexposure condition were presented a piece of 40 mg ground raw beef once a week for 15 weeks. Other foods were not given throughout the experiment. Newts in the Non-preexposure condition were given three 13 mg (wet weight) food pellets instead of the raw beef. In conditioning after the pre-exposure period, newts in both conditions were allowed to eat pieces of 40 mg raw beef (CS) scattered in a water tank for one hour. Immediately after the CS presentation, i.p. injections of LiCl (0.15M, 190 mg/kg) or saline (190 mg/kg) were given to Experimental and Control conditions, respectively. In the test conducted 12 days after the conditioning, rats in the Experimental conditions consumed less amount of CS food than in the Control conditions. However, any inhibitory effects by preexposure of CS food on conditioning were not observed. That is, any significant differences of strength of food aversion conditioning were not observed between Preexposure and Non-preexposure conditions. These results suggest absence of latent inhibition in food aversion conditioning in Japanese fire-bellied newts.