Daily treatment with alfa-naphthoflavone enhances follicular growth and ovulation rate in the rat

KARINA ANDREA BARREIRO; MARIA PAULA DI YORIO; ROMINA DOLORES ARTILLO GUIDA; DANTE AGUSTIN PAZ

TOXICOLOGY AND APPLIED PHARMACOLOGY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Amsterdam; Año: 2011 vol. 252 p. 11 - 17

0041-008X

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor and the first protein involved in a variety of physiological and toxicological processes, including those of xenobiotic metabolizing enzymes. AhR has been found in the ovary of many species and seems to mediate the ovarian toxicity of many environmental contaminants, which are AhR ligands. However, the role of AhR in the ovarian function is unknown. Therefore, the aim of this work was to study the action of alfa-naphthoflavone (alfa-NF), known to be an AhR antagonist, on both follicular growth and ovulation. Immature Sprague?Dawley rats were daily injected intraperitoneally with alfa-NF (0.1?80 mg/kg) or vehicle for 12 days, and primed with gonadotrophins (eCG/hCG) to induce follicular growth and ovulation. Ovaries were obtained 20 h after hCG administration. By means of immunohistochemistry, we found that the numbers of primordial, primary and antral follicles were increased in rats treated with 80 mg/kg alfa-NF and that there were no differences with other doses. Likewise, the ovarian weight and the ovulation rate, measured by both number of oocytes within oviducts and corpora lutea in ovarian sections, were increased when the rats received either 1 or 10 mg/kg daily. Although further studies are necessary to know the mechanism of action of alfa-NF, it is possible that the different ovarian processes can be differentially responsive to the presence of different levels of alfa-NF, and that the same or different endogenous AhR ligands can be involved in these ovarian processes in a cell type-dependent manner.