Effects of space flight on sperm function and integrity: A systematic review

Area of Science:

• Space Medicine
• Reproductive Biology
• Astrobiology

Background:

• Human space exploration, including Mars settlement, necessitates understanding spaceflight's impact on human physiology.
• Male reproductive health, specifically sperm function, is crucial for procreation and may be compromised by space environments.

Purpose of the Study:

• To systematically review and synthesize existing literature on the effects of spaceflight, microgravity, and ionizing radiation on male reproductive parameters.
• To identify potential risks to male fertility in space and inform the development of protective strategies.

Main Methods:

• A systematic literature search was conducted using PRISMA guidelines across major databases (e.g., PubMed).
• MeSH terms included "spermatozoa", "microgravity", and "ionizing radiation".
• Included studies focused on male reproductive parameters such as sperm motility, count, DNA fragmentation, hormonal levels, and testicular histology.

Main Results:

• Microgravity and ionizing radiation exposure decreased sperm motility.
• Microgravity alone reduced total sperm count.
• Both microgravity and ionizing radiation increased sperm DNA fragmentation.
• Microgravity exposure led to decreased testosterone levels and testicular weight.

Conclusions:

• Available evidence indicates that microgravity and ionizing radiation pose significant risks to male reproductive health.
• There is a critical need for further research and the development of countermeasures to mitigate these adverse effects for long-duration space missions.