Effect of long-term exposure to combinations of growth promoters in Long Evans rats: Part 2: ovarian morphology Original Research Article

The aim of the study was to investigate the effects of long-term exposure (45 days) to growth promoters: clenbuterol (CB, 1 mg kg−1 bw) and/or dexamethasone (DEX, 0.1 mg kg−1 bw), in ovarian morphology, and the possibility of recovery after the withdrawal of drug treatment. Animals were sacrificed at different days of withdrawal (W0, W5, W10, W15 and W20). Ovaries of CB treatment showed typical features of long-term administration of β-agonists at W0 with antral and atretic follicles, and the absence of corpora lutea, indicating disrupted cyclicity of rats. However, at W20 ovaries showed cyclic features with corpora lutea, antral follicles, and even recently ovulated follicles. Ovaries of CB+DEX and DEX treatments showed features of disrupted cyclicity at W0 also with cystic follicles, and fewer healthy antral follicles than those of treatment I, these same features also being observed at W20. Immunohistochemistry (IHC) of ovaries denoted that neither positive staining nor localization of steroidogenic enzymes were affected by treatments. We can conclude that treatments can disrupt the reproductive function.