Comparative Behavioral Effects Between Synthetic 2,4,5-trimethylthiazoline (TMT) and the Odor of Natural Fox (Vulpes vulpes) Feces in Mice

Synthetic 2,4,5-trimethylthiazoline (TMT)-a component of red fox ( Vulpes vulpes ) feces-is frequently used to induce unconditioned fear in rodents. Surprisingly, direct comparison between TMT and natural fox feces odor is almost nonexistent. In this study, Experiment 1 compared the avoidance in relation to TMT concentration, natural fox feces, and gender of fox and mice. Results show that the avoidance is (a) higher with either pure or 50% TMT as compared to natural fox feces, whereas the difference is slight with 10% TMT, and (b) significantly higher for the female mouse group compared to the male mouse group with TMT as well as natural fox feces. In addition, no clear difference in effect was observed between male and female fox feces. Experiment 2 compared behavioral parameters recorded as an index of fear and anxiety, general activity, and avoidance in elevated plus-maze and open-field chamber between 10% TMT and natural fox feces in relation to the estrus cycle of the mice. Results show no cycle period effect-except for the avoidance parameter "distance to odorant"-and no different effects between 10% TMT and natural fox feces except for freezing.