MORPHOLOGICAL ANALYSIS OF TRABECULAR BONE IN PERSISTENT ESTROUS RAT MODELS INDUCED BY SEXUAL STEROIDS: PRELIMINARY RESULTS

Abstract

Aims: Our aim is to analyze how is the trabecular bone in persistent estrous rat models that mimic polycystic ovary syndrome. Methods: 15 animals received between 0-3 days of age only one subcutaneous injection of the following substances according with the experimental groups: testosterone propionate (1.25 mg/0.1 mL of vehicle) (testosterone group - TG; n 05), estradiol benzoate (0.5 mg/0.1 mL of vehicle) (estradiol group - EG; n 05), vehicle (0.1 mL) (control group - CG; n 05). Estrous cycle of each rat was assessed by the vaginal smears taken between 75-90 days old. The weight of the animals was done once a week between the birth and 84 days old. Animals were previously anaesthetized and sacrificed with 90 days old and ovary and femur were removed for histological routine. The histological sections were stained with hematoxylin-eosin for evaluating cysts in ovary and trabecular bone structure. ANOVA supplemented by Tukey’s multiple comparisons test was performed to evaluate the weight of the animals. Results: Animals of CG had normal estrous cycle, but EG and TG animals had closed vagina, and because ofthis vaginal smears were not collected. Ovarian histology revealed that EG and TG have cysts and did not have corpora lutea, which indicates that these animals were in chronic anovulation state (persistent estrous). CG ovaries showed corpora lutea as well follicles at different stages of development. Regarding the animals’ weight, EG exhibits the larger mean (320.1± 13.2 g), followed by TG (298.2±19.8 g) and after by CG (260.2±15.3 g). Statistical comparison between CG and EG weight showed significant difference (p<0.05) as well as the comparison between CG and TG (p<0.05). However, there was no significant difference between TG and EG. Evaluation of trabecular bone showed that control group presented great amount of bone trabeculae, as well as preserved thickness and connectivity. EG showed less trabecular connectivity, but also showed great amount of trabecular bone and preserved thickness. The amount of bone trabeculae and trabecular thickness and connectivity were increased in TG in relation to CG. Conclusion: We concluded that testosterone persistent estrous rat model presents improved trabecular bone quality and the changes induced by estradiol in perinatal period seems to be restricted to less trabecular connectivity, but we are doing the morphometric analysis to achieve a better conclusion.