Effects of testosterone on cancellous bone, marrow adipocytes, and ovarian phenotype in a young female rat model of polycystic ovary syndrome

Objective: To investigate the effects of testosterone on cancellous bone and marrow adipocytes in a young female rat model of polycystic ovary syndrome (PCOS). Design: Comparative and controlled study. Setting: University animal res laboratory. Patient(s): Fifty-one Sprague-Dawley rats. Intervention(s): The rats were divided into four groups based on the day of testosterone propionate (00.1 mg/weight (g)) injection no testosterone treatment (control group, C); injected on the ninth day after birth (9D): injected 4 weeks after birth (4W); and injected 8 weeks after birth (8W). About 16 weeks after birth, all animals were killed. Main Outcome Measure(s): Bone mineral density (BMD) and bone and fat histomorphometry for the proximal tibia and serum hormonal parameters were measured. Result(s): The ovaries of group 9D showed many cystic follicles without corpora lutea. The BMD of group 9D (3.309 +/- 0.023 g/cm(2)) was significantly higher than the other groups groups (CONT, 0.262 +/- 0.017; 4W, 0.256 +/- 0.017; 8W, 0.256 +/- 0.022 g/cm(2); P < .0001). Based on bone histomorphometry, group 9D had a higher bone volume (BV/TV), lower bone formation (OV/BV, OS/BS, sLS/BS, MAR, BFR/BS), lower bone resorption (ES/BS, Oc.S/BS), and lower rate of longitudinal growth compared to the other groups. Based on fat histomorphometry group 9D had a lower bone fat volume and number of fat cells in the bone marrow compared to the other groups. On the other hand, groups 4W and 8W showed similar values of bone and fat histomorphometric parameters to group C. Conclusion(s): Female rats receiving testosterone within nine days of birth develop polycystic ovaries, high bone volume, low bone turnover, and lower fat content in the bone marrow.