Aim: To investigate the reproductive organs in young male rats and those with age-related involution of reproductive organs after long-term administration of letrozole, a steroid aromatase inhibitor, followed by its withdrawal.
The experiments were carried out on Wistar rats aged 5 to 15 months, who were gavaged with letrozole at a dose of 1 mg/kg b. w every other day for 3 months and then ceased for 2 months. The levels of testosterone and estradiol in the blood plasma were determined using immunoassays. Spermatozoa concentrations in epididymal washes were measured. The gonads and ventral prostate morphology were studied, as well as the testicles and accessory sexual glands. The study's findings were compared to those of control animals of the same age.
As a result of letrozole treatment, the ratio of testosterone to estradiol in the blood plasma of aged rats rose. In the epididymis, the average number of spermatozoa increased by 28%. Leydig cells were functionally activated, according to histological examination, with significant delays in involutive changes in their number and form. Some of the Leydig cells had functional depletion symptoms. Letrozole raised the relative weights of the coagulation gland by 40%, seminal vesicles by 31%, and the ventral prostate by 33% as compared to control rats. Two months after the letrozole was stopped, there were no indicators of difference between the letrozole-treated and control animals. In young rats, the effects of letrozole were almost imperceptible.
Conclusions: Letrozole raises the testosterone/estradiol ratio in blood plasma, spermatozoa content in epididymia, and the weights of androgen-dependent accessory sexual glands in male rats with age-related involution of the reproductive system. After that, age-related morphological changes in the gonad and prostate gland slow down. Letrozole's effects on reproduction are reversible.
Author(s) Details:
A. G. Reznikov
V. P. Komisarenko Institute of Endocrinology and Metabolism, National
Academy of Medical Sciences of Ukraine, 69 Vyshgorodska str., Kiev, 04114,
Ukraine.
O. V. Sachynska,
V. P. Komisarenko Institute of Endocrinology and Metabolism, National Academy
of Medical Sciences of Ukraine, 69 Vyshgorodska str., Kiev, 04114, Ukraine.
L. I. Polyakova,
V. P. Komisarenko Institute of Endocrinology and Metabolism, National Academy
of Medical Sciences of Ukraine, 69 Vyshgorodska str., Kiev, 04114, Ukraine.
O. A. Faliush,
V. P. Komisarenko Institute of Endocrinology and Metabolism, National Academy
of Medical Sciences of Ukraine, 69 Vyshgorodska str., Kiev, 04114, Ukraine.
A. V. Yanishevskiy,
V. P. Komisarenko Institute of Endocrinology and Metabolism, National Academy
of Medical Sciences of Ukraine, 69 Vyshgorodska str., Kiev, 04114, Ukraine.
