Age-related decline in behavior and reproductive health in male mice.

Research on reproductive advanced age has predominantly focused on women due to their biological clock. The impact of paternal senescence on fertility and offspring is still poorly understood. In this study, we characterized the effects of aging on sexual behavior and reproductive characteristics using male mice aged 4 months as a control, compared to mice aged 19 and 24 months. In the first experiment, we observed that reproductive interest and locomotor activity were reduced in older males, accompanied by reduced serum testosterone levels and testicular weight. We observed increased sperm morphological anomalies, protamine deficiency, and reduced sperm capacitation in aging mice. Aging also influenced cleavage, blastocyst and in vitro embryo development rates; embryo kinetics, and initial cell differentiation. In the second experiment, aging promoted smaller, lighter fetuses and a lower fetal weight ratio. In conclusion, an increased age impaired sexual behavior, sperm function, and embryo and fetal development.