Mounting in female hamsters: Effects of different hormone regimens

Abstract

Adult female hamsters have substantial capacity to display male behavior without perinatal androgen administration and apparently without perinatal exposure to gonadal steroids. Seventy-two ovariectomized females were tested for male behavior during chronic treatment with either testosterone (T, N = 8); androstenedione (AD, N = 7); dihydrotestosterone (DHT, N = 8); estradiol (E 2, N = 7); T + E 2 (N = 9); AD + E 2 (N = 6); DHT + E 2 (N = 7); or no hormone (NoH, N = 19). Eighty-three percent of the females treated with T, T + E 2, AD + E 2, or DHT + E 2 mounted during at least one test, and 70% displayed the intromission pattern; there were no significant differences among these treatment conditions. Forty-two percent of E 2-treated females, 14% of AD-treated females, none of the DHT-treated females, and one of the NoH females mounted; these treatments were significantly less effective than T or any of the androgen-plus-estrogen combinations. Females treated with E 2 or AD + E 2 displayed lordosis responses when tested for female behavior, but females treated with T + E 2, DHT + E 2, T, DHT or NoH did not. In the hamster the capacity for the execution of male behavior develops independent of early androgen, and only the arousability of the system by hormonal and external stimulation is sex dimorphic.