ABSTRACT
1. The purpose of the present investigation was to study the effect of ß-estradiol crystals implanted in the corticomedial area of the amygadaloid body on the sexual behavior of castrated male rats. 2. The animals were divided into the following groups: group I (N=9), castrated rats; group II (N=4), rats which had been castrated and stereotaxically implanted with cholesterol, both groups being used as controls; group III (N=6), castrated rats con estradiol implants. Latency to the first anogenital exploration, latency to the first mount and mount frquency were determined during the pre-castration and post-castration phases and after the material had been implanted in groups II and III in 10-min observation sessions. 3. There was diminished sexual behavior of the animals in group I without spontaneous recurrence within the period observed. Group II animals, who had undergone implantation of cholesterol, an inert substance, maintained low levels of sexual behavior (post-castration 0.8 ñ 7 vs 0.0 ñ 0.0 and 0.5 ñ 0.5 on the 6th and 9th day afther implantation, repectively). Group III animals presented a gradual increase in the number of mounts (from post-castration 1.2 ñ 0.5 to 6.5 ñ 2.7 and 4.1 ñ 1.0 on the 6th and 9th day after implantation, respectively) and a decrease of mount latency (from post-castration 431.2 ñ 55.9 to 226.1 ñ 119.6 and 51.0 ñ 28.9 on the 6th and 9th day after implantation, respectively) reaching pre-castration levels on the 6th and 9th day after ß-estradiol implantation. 4. We conclude that, under the effect of estradiol, the amygdaloid region can modulate male sexual behavior, thus injdicating a physiological role for estradiol receptors present in this area