Temperature Elevation during Semen Delivery Deteriorates Boar Sperm Quality by Promoting Apoptosis

Area of Science:

• Animal Reproduction
• Sperm Biology
• Molecular Biology

Background:

• Artificial insemination in pigs relies on high-quality boar sperm delivery.
• Semen transport in warm conditions can compromise sperm viability and fertility.

Purpose of the Study:

• To assess the impact of elevated temperatures during semen delivery on boar sperm quality and function.
• To investigate the molecular mechanisms, including apoptosis and protein expression, involved in sperm's response to heat stress.

Main Methods:

• Boar semen was subjected to simulated delivery conditions (37°C for 24h in a Styrofoam box) followed by refrigeration (17°C).
• Sperm quality (motility), apoptosis markers (Bax, Caspase 3), phosphorylated AMPK, and heat shock proteins (HSP70, HSP90) were analyzed using CASA, flow cytometry, and Western blotting.

Main Results:

• Elevated temperatures significantly reduced boar sperm quality and motility after 14 hours, with no recovery upon cooling.
• Heat stress increased sperm apoptosis (Bax, Caspase 3) and altered AMPK phosphorylation.
• Expression of HSP70 and HSP90 significantly increased with rising temperatures.

Conclusions:

• Temperature increase during boar semen delivery severely damages sperm quality and function by inducing apoptosis.
• HSP70 and HSP90 may play a role in boar sperm thermotolerance, potentially through AMPK activation and anti-apoptotic pathways.