Department of Animal Reproduction, INIA, Madrid, Spain.
Centro de Enseñanza, Investigación y Extensión en Producción Ovina, FMVZ-UNAM, Tres Marías, Morelos, Mexico.
Andrology. 2021 Jul;9(4):1242-1253. doi: 10.1111/andr.12998. Epub 2021 Mar 22.
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.
The present work examines the influence of induced changes in testosterone secretion on sperm variables following conventional slow freezing and ultra-rapid freezing, using the Iberian ibex as an experimental model.
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).
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 ultra-rapid 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).
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.
最近的研究表明，循环睾酮浓度可能会影响精子冷冻保存的存活能力。然而，很少有尝试来证实这种关系。野生反刍动物的生殖功能具有明显的季节性变化，其血浆睾酮浓度有强烈的年度变化。
本研究以伊比利亚羱羊为实验模型，检验诱导的睾酮分泌变化对常规慢速冷冻和超快速冷冻后精子变量的影响。
在第一个实验中，在发情期（12 月）中期使用抗雄激素环丙孕酮（CA）降低睾酮水平。在第二个实验中，在发情期末期（1 月）通过使用雄激素丙酸睾酮（TP）增加睾酮水平。
12 月，未处理雄性的血液和精液中睾酮浓度高于 CA 处理雄性（p<0.001 和 p<0.05）。与对照组相比，1 月 TP 处理动物的血浆睾酮浓度较高，但精液中睾酮浓度较低（p<0.01 和 p<0.001）。TP 处理雄性的精囊比未处理雄性大（p<0.05）。当给予 CA 时，与对照组相比，精子活力提高（p<0.05），无论采用哪种冷冻方案。对于超快速冷冻程序，当给予 TP 时，运动活力的冷冻抗性比降低（p<0.05）。在 CA 处理结束后的 50 天内，新鲜精子形态计量变量值下降（p<0.001），而在 TP 处理结束后相同时间内增加（p<0.001）。
循环睾酮浓度似乎影响精子的冷冻抗性。这可以解释一些物种的精子可冻性的季节性变化，而与新鲜精子质量无关。
