ABSTRACT
Letrozole comprises a non-steroid aromatase inhibitor that has been applied as a preventive for many uses, such as breast cancer prevention, treatment of hormonal dysfunction, and male infertility. Precisely in Northeast Brazil, ovine consist of the leading livestock produced, and their reproduction in captivity has been demonstrated difficult. Thus, we hypothesized whether the application of letrozole will improve male sheep reproduction. One group of 6 animals received a daily dosage of 0.5mg/Kg of letrozole for 60 days, while the other six animals were used as control. Samples were collected from control and treated animals after 30 and 60 days of the experiment. Blood samples were collected to measure the steroid hormone levels. Semen was collected from control and treated groups using an artificial vagina and cryopreserved for spermatozoa morphology and CASA analysis. The testicles were collected for histological analysis, gene expression, and immunohistochemistry of P450aromatase protein. Hormone levels demonstrate no differences in the estradiol/testosterone levels among the control and both treated groups. Immunohistochemistry analysis revealed the presence of P450aromatase protein in spermatogonia cells and Leydig cells in the control and treated groups in both periods analyzed. Moreover, there were no differences in the P450aromase gene expression in the control and treated group. Morphological analysis of the spermatozoa revealed that letrozole treatment did not affect mitochondrial activity or cause any deformities. In addition, motility parameters in the sperm from the treated group were not affected by letrozole treatment compared to the control group. Morphological analysis of the testis demonstrated that letrozole treatment increase the seminiferous tubule area but no signs of germ cell damage. Our results show that letrozole has a morphological effect on the testicles in the ovine model but no pathological or severe effect caused by hormone level imbalance. Overall, letrozole comprises a non-steroid aromatase inhibitor, which can be applied to ovine reproduction.
ABSTRACT
The study aimed at evaluating the testicular structure and spermatogenesis of Santa Inês and Santa Inês and Dorper crossbred sheep. Sixteen testicles of the animals under study were used, in order to evaluate the volumetric proportion, the diameter of the tubules, the height of seminiferous epithelium, the frequency of stages of the seminiferous epithelium cycle and the spermatogenic yield. The data were submitted to Student-Newman-Keulstestat 5% significance. The tubular diameter was 173.12 ± 29.09 µm and 185.71 ± 29.7 µm, and the height of the seminiferous epithelium was 52.29 ± 9.98 µm and 56.68 ± 11.25 µm, for the crossbred and the Santa Inês, respectively. There was no difference between the testicular compartments and the frequency of the stages of the seminiferous epithelium cycle between the groups. Santa Inês sheep presented a number of 15.36 ± 4.49 spermatocytes in the pre-leptotene/leptotene stage and 27.42 ± 6.65 spermatocytes in the pachytene, whereas the crossbred presented 13.18 ± 5.19 and 23.48 ± 7.80, respectively. The crossbred showed higher meiotic yield (3.98 ± 1.28) and spermatogenesis yield (3.71 ± 1.02). It is concluded there are differences in testicular morphology and spermatogenesis between Santa Inês sheep and crossbred Dorper/Santa Inês, indicating that the crossbreeding between the Santa Inês and Dorper animals allows a gain in the reproductive potential.
