Endocrine Abstracts

Mitotane (MTT) currently represents the treatment of choice for adrenocortical carcinoma (ACC). Clinical evidence shows the occurrence of hypogonadism following treatment with this drug, observed more frequently in male patients. The aim of the study, therefore, was to evaluate the impact of MTT treatment on male gonadal function on adult CD1 mice. At the end of the 45 days of treatment, testes were collected for morphological examination, and a blood sample of each animal was retrieved to evaluate serum hormone levels. Serum testosterone was significantly lower in MTT-treated animals than the control siblings. The testis of the MTT-exposed group showed several degrees of damage: disorganization of the germinal epithelium, a pronounced alteration of the spermatogenic process with a reduction of spermatozoa in the lumen, absence of lumen and a less compact interstitial space and a thickness of the albuginea. Molecular analysis on the interstitial compartment revealed the expected significant decline in mRNA expression of 3βHsd and Insl3 in MTT-treated mice, confirming an impairment of androgens production. The expression of mRNA of Fsh-R was only slightly down modulated by treatment with MTT, but was not statistically different, proving that Sertoli cells are not the main target of the drug and the alteration of spermatogenesis is not related to Sertoli cell damage. Moreover, the evaluation of the specific gene expression for different stages of germ cell differentiation, stimulated by Retinoic Acid 8 (Stra8), expressed in differentiating spermatogonia and Heat shock protein A 2 (HspA2), a marker of meiotic cells, showed no alteration in the expression of Stra8 and a decrease of HspA2 mRNA in the testes of MTT-treated mice, demonstrating that differentiating spermatogonia are not affected by the drug treatment while impairment of the meiotic progression of germ cells was observed. Finally, the concentration of sperm collected from epididymis cauda was significantly lower in MTT treated animals than in the control group. Moreover, the administration of MTT caused a significant increase in the percentage of spermatozoa with abnormal chromatin structure defined by the DNA fragmentation index (%DFI) compared to the untreated animals. The testosterone replacement therapy only restored some of these parameters.

In conclusion, we demonstrate the negative effects of the MTT treatment on the male reproductive system, including changes in the morphology of testicular tissue and reduction of sperm concentration and sperm quality.