Schmidt Jonathan A, Oatley Jon M, Brinster Ralph L
Department of Animal Biology, University of Pennsylvania, Philadelphia, PA, USA.
Biol Reprod. 2009 May;80(5):1009-14. doi: 10.1095/biolreprod.108.073619. Epub 2009 Jan 21.
Reproductive aging of the male is characterized by decreasing fertility; however, factors that protect against reproductive aging in the male are largely unknown. Previous work has demonstrated that both female presence and aging have a dramatic effect on fertility in the male; yet, the effect of female presence on fertility in the aging male mouse is unknown. The objective of this work was to determine the effect of long-term isolation or cohabitation with females on fertility in aged male mice. Male mice were housed with or without females until between 16 and 32 mo of age. Males were subjected to fertility tests at specific ages, after which serum and testes were isolated for radioimmunoassay and histological analysis. We show that male mice continuously housed with females remain fertile longer ( approximately 20% of the reproductive lifespan) than male mice housed alone. Fertility became significantly reduced 6 mo sooner for males housed alone compared with males housed with females; however, the rate of decline was the same for males housed with or without females once fertility began to decrease. Testis weight decreased as the mice aged, and a nearly significant positive effect of female presence was observed. Additionally, histological analysis indicated that abnormal spermatogenesis occurred sooner in isolated males, suggesting that defects in spermatogenesis may play a role in the greater decrease in fertility in isolated males. These results have significant implications for the maintenance of male fertility in wildlife, livestock, and human populations.
雄性生殖衰老的特征是生育能力下降；然而，保护雄性免受生殖衰老影响的因素在很大程度上尚不明确。先前的研究表明，雌性的存在和衰老都会对雄性的生育能力产生显著影响；然而，雌性的存在对衰老雄性小鼠生育能力的影响尚不清楚。这项研究的目的是确定长期与雌性隔离或同居对老年雄性小鼠生育能力的影响。将雄性小鼠与雌性小鼠一起饲养或单独饲养，直至16至32月龄。在特定年龄对雄性小鼠进行生育能力测试，之后分离血清和睾丸进行放射免疫分析和组织学分析。我们发现，与单独饲养的雄性小鼠相比，持续与雌性小鼠一起饲养的雄性小鼠保持生育能力的时间更长（约为生殖寿命的20%）。与与雌性小鼠一起饲养的雄性相比，单独饲养的雄性小鼠生育能力显著降低的时间提前了6个月；然而，一旦生育能力开始下降，无论是否与雌性小鼠一起饲养，雄性小鼠生育能力下降的速率是相同的。随着小鼠年龄的增长，睾丸重量下降，并且观察到雌性存在有近乎显著的积极影响。此外，组织学分析表明，隔离饲养的雄性小鼠精子发生异常出现得更早，这表明精子发生缺陷可能在隔离饲养的雄性小鼠生育能力更大幅度下降中起作用。这些结果对野生动物、家畜和人类种群中雄性生育能力的维持具有重要意义。
