Impaired reproduction in adult male, but not female, rats following juvenile treatment with the aromatase inhibitor, exemestane

Morphological and morphometric changes and epithelial apoptosis are induced in the rat epididymis by long-term letrozole treatment

The epididymis is an organ that plays a key role in sperm maturation. The aim of this study was to examine the association between the chronic treatment of mature male rats with letrozole and morphological evaluation and morphometric values of epididymis as well as changes in the number of apoptotic cells in epididymal epithelium. Adult rats were treated with letrozole for 6 months and the epididymis weight, morphology, morphometric values and the number of apoptotic cells in  the epithelium were examined. Long-term aromatase inhibition resulted in presence of intraepithelial clear vacuoles, hyperplasia of clear cells and a hyperplastic alteration in the epithelium known as a cribriform change. Moreover, changes in diameters of the epididymal duct and the epididymal lumen and changes in the epididymal epithelium height were observed. The number of apoptotic epithelial cells was increased in letrozole-treated group. It can be indicated that chronic treatment with letrozole can affect morphology, morphometric values and apoptosis in the epididymis of adult male rats. Observed changes are similar to that observed in the aging processes and may also be important for patients treated with aromatase inhibitors.

Teasing out the role of aromatase in the healthy and diseased testis

Scientific discoveries over the past decade have shifted the stereotypical view of androgens as male hormones and estrogens as female hormones. It is now recognized that a delicate balance of both androgens and estrogens, a process controlled by aromatase, is fundamental for normal testicular development and fertility. While the site-specific actions of these two classes of steroids within the testis are becoming better documented, the role and regulation of estrogen biosynthesis by aromatase within the testis remains unclear. The majority of data comes from a wide range of animal species, particularly genetically modified mouse models; aromatase knockout (ArKO) and overexpressing (AROM(+)), with limited information on humans, however the existence of congenital aromatase mutations has provided some insight into its effects on individual parameters of the testis. This review dissects out the localization and activity of aromatase in the healthy and diseased testis, addresses the cellular insult to the testis that occurs in its absence and over abundance and proposes potential molecular mechanisms of aromatase regulation in the testis.