Influence of circulating testosterone concentration on sperm cryoresistance: The ibex as an experimental model

Abstract

Background: Recent studies have noted that the circulating testosterone concentration may affect the ability of spermatozoa to survive cryopreservation. However, few attempts to confirm such a relationship have been made. Wild ruminant species have very marked seasonal changes in their reproductive function and strong annual changes in their plasma testosterone concentration. Objectives:The present work examines the influence of induced changes in testosterone secretion on sperm variables following conventional slow freezing and ultrarapid freezing, using the Iberian ibex as an experimental model. Materials and Methods:In a first experiment, testosterone levels were reduced in the middle of the rutting season (December) using the antiandrogen cyproterone acetate (CA). In a second experiment, testosterone levels were increased at the end of the rutting season (January) via the use of the androgen testosterone propionate (TP).Results: During December, the testosterone concentration was found to be higher in the blood and seminal plasma of untreated males than in those of CA-treated males (p < 0.001 and p < 0.05, respectively). Compared with controls, the TP-treated animals had higher blood plasma testosterone concentrations but lower seminal plasma testosterone concentrations during January (p < 0.01 and p < 0.001, respectively).The seminal vesicles of the TP-treated males were larger than those of untreated males (p < 0.05). When CA was administered, sperm viability improved compared with controls (p < 0.05), irrespective of the freezing protocol followed. For the ultrarapid freezing procedure, the cryoresistance ratio for motility decreased when TP was administered (p < 0.05). The values for fresh sperm morphometric variables decreased during the 50 days after the end of CA treatment (p < 0.001) and increased over the same time after the end of TP treatment (p < 0.001). Discussion and Conclusion:The circulating testosterone concentration appears to influence sperm cryoresistance. This may explain the seasonal changes seen in sperm freezability in some species, independent of fresh sperm quality.

Effect of Testosterone, Dihydrotestosterone, Estradiol and Cortisol on the Quality of Fresh and Cryopreserved Stallion Sperm

“…Coloma et al (2010) revealed that high levels of testosterone in the Iberian ibex blood plasma were associated with a decrease in progressive sperm motility and a decrease in acrosome and membrane integrity, and this relationship is characteristic only for the frozen-thawed sperm. Bóveda et al (2021) also found a reduction in the concentration of testosterone in the blood plasma of Iberian ibex and it increased with the sperm cryostability duration increases and vice versa. Moreover, these changes most likely occur at the final stage of sperm maturation in cauda epididymis and secretion of the sperm and may be associated with remodeling of the protein and lipid components of the sperm membrane.…”

Expression of Aquaglyceroporins in Spermatozoa from Wild Ruminants Is Influenced by Photoperiod and Thyroxine Concentrations

“…The influence of photoperiod/melatonin on AQP expression might be indirectly exerted via changes in the testosterone concentration, which in turn might be associated with reduced sperm cryoresistance. Indeed, it is known that high testosterone levels negatively affect sperm cryoresistance in both the examined species [ 30 ]. The present findings suggested that the negative influence of testosterone on sperm freezability may be mediated via AQP expression.…”

Single or repeated immunization against GnRH fails to completely abolish spermatogenesis in dwarf bucks (Capra hircus)

“…Despite androgens have an important role in the activity of seminal vesicles and bulbourethral glands, their size was not modified after immunization against GnRH. It has been shown that even shortterm treatments with antiandrogens-that is, cyproterone, acetatereduce the area of seminal vesicles in wild goats (Bóveda et al, 2021).…”