Sex steroids possess distinct stimulus properties in female and male mice.

Very few studies have investigated the aversive properties of sex steroids in animals. We studied these properties by testing oestradiol-3-benzoate, testosterone-propionate and progesterone in a conditioned taste aversion set-up, in intact female and male mice. Oestradiol-3-benzoate induced a taste aversion in both female and male mice; however, testosterone-propionate and progesterone had an effect only in females. These results show that sex steroids have intrinsic aversive properties. The different effects of the steroids in males and females cannot simply be explained by nausea induction or novelty.