TESTOSTERONE STIMULATES ULTRASOUND PRODUCTION BY MALE HAMSTERS

Rates of ultrasound production by male hamsters were observed before, during, and after presentations of stimulus females and synthetic ultrasounds. Following castration, oil-treated control males showed decreased rates of ultrasound production, especially in tests with females. In contrast, castrates treated with 200 μg/day of testosterone propionate called at rates which equaled or exceeded their own preoperative levels and which consistently exceeded the postoperative call rates of the oil controls. These results show that ultrasound production by male hamsters is stimulated by gonadal androgens, and they support the interpretation of these signals as courtship displays. © 1979.