Nandrolone Decanoate Causes Pathologic Changes in the Uterus of Surgically Postmenopausal Female Cynomolgus Macaques

OBJECTIVE: To determine the effects of the androgenic anabolic steroid nandrolone decanoate on uterine endometrium and myometrium and on the mammary gland of female cynomolgus macaques by using morphologic, histomorphometric, and histopathologic determinations. DESIGN: Histologic and histomorphometric measurements were performed on uteri and mammary glands that were collected at necropsy from animals that had been used in a long-term experiment to examine the effects of nandrolone decanoate on bone and coronary arteries. The animals were surgically postmenopausal cynomolgus macaques randomized into four treatment groups: (a) intact sham ovariectomized (sham; n = 12), (b) ovariectomized (OVX; n = 15), (c) ovariectomized + nandrolone decanoate for 2 years (OVX + ND; n = 14), and (d) ovariectomized + nandrolone decanoate for 1 year, beginning 1 year after ovariectomy (OVX + NDdelay; n = 11). Intramuscular injections of nandrolone decanoate (25 mg every 3 weeks) were given to the two nandrolone-treated groups of animals (OVX + ND and OVX + NDdelay): one starting 3 weeks after ovariectomy and continuing for 2 years and the other group 1 year after ovariectomy. The sham and OVX groups were given an intramuscular injection of sterile vehicle every 3 weeks. RESULTS: Nandrolone treatment was moderately uterotropic in all treated versus ovariectomized animals. Changes induced were an increase in uterine weight, endometrial thickness, and glandular area, and a high incidence of mucometra. Glandular architecture was altered by nandrolone treatment such that glands extended into the myometrium (producing an adenomyosis-like lesion). Mammary gland changes were mild and equivocal. CONCLUSION: Nandrolone induced pathologic changes in ovariectomized monkeys similar to adenomyosis in the uterus.