The purpose of the present investigation was to study the effect of beta-estradiol crystals implanted in the corticomedial area of the amygdaloid 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 with estradiol implants. Latency to the first anogenital exploration, latency to the first mount and mount frequency 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 +/- 0.7 vs 0.0 +/- 0.0 and 0.5 +/- 0.5 on the 6th and 9th day after implantation, respectively). Group III animals presented a gradual increase in the number of mounts (from post-castration 1.2 +/- 0.5 to 6.5 +/- 2.7 and 4.1 +/- 1.0 on the 6th and 9th day after implantation, respectively) and a decrease of mount latency (from post-castration 431.2 +/- 55.9 to 226.1 +/- 119.6 and 51.0 +/- 28.9 on the 6th and 9th day after implantation, respectively) reaching pre-castration levels on the 6th and 9th day after beta-estradiol implantation.(ABSTRACT TRUNCATED AT 250 WORDS)
