Paternal hypoxia exposure impairs fertilization process and preimplantation embryo development

Area of Science:

• Reproductive Biology
• Environmental Physiology
• Developmental Biology

Background:

• Environmental hypoxia is linked to human and animal fertility issues.
• Chronic hypoxia negatively affects spermatogenesis and sperm motility.
• The impact of paternal hypoxia on fertilization and early embryo development remains unclear.

Purpose of the Study:

• To investigate the effects of paternal hypoxia on sperm quality.
• To evaluate the impact of hypoxia on zygotic DNA methylation.
• To assess the influence of paternal hypoxia on blastocyst formation.

Main Methods:

• Male mice were exposed to high altitude (3200 m) for 7 or 60 days.
• Sperm quality, fertility, in vitro fertilization (IVF) rates, and blastocyst formation were assessed.
• Immunohistochemical staining examined pronuclear formation and imprinted gene expression in early embryos.

Main Results:

• Hypoxia-exposed males showed reduced fertility due to impaired sperm motility and function.
• In vitro fertilization experiments revealed significant reductions in cleavage (30%) and blastocyst (70%) rates after 60 days of hypoxia.
• Paternal hypoxia disturbed pronuclear formation and reduced imprinted gene expression in early mammalian embryos.

Conclusions:

• Paternal hypoxia exposure impairs sperm function in male mice.
• Hypoxia affects critical events in early mammalian embryo development, including fertilization and blastocyst formation.
• These findings highlight the detrimental effects of environmental hypoxia on reproductive outcomes.