Sperm chemorepulsion, a supplementary mechanism to regulate fertilization

Area of Science:

• Reproductive Biology
• Cellular Signaling
• Sperm Motility

Background:

• Chemotaxis, including chemoattraction and chemorepulsion, guides cell movement along molecular gradients.
• While chemoattraction is studied in spermatozoa for oocyte finding, chemorepulsion has not been verified.
• Unicellular and other mammalian cells exhibit chemorepulsive behaviors.

Purpose of the Study:

• To investigate whether human spermatozoa are capable of chemorepulsive behavior.
• To determine if capacitated human spermatozoa can be repelled by specific chemical cues.
• To explore the potential biological and clinical implications of sperm chemorepulsion.

Main Methods:

• In vitro study utilizing human, rabbit, and mouse spermatozoa.
• Sperm selection assay (SSA) and video-microscopy with computer motion analysis were employed.
• Tested repulsion against synthetic progesterone receptor ligands (sPRL) and zinc, with and without progesterone gradients.

Main Results:

• Capacitated human spermatozoa demonstrated chemorepulsion from sPRL and zinc.
• Repulsive movement patterns were observed against ulipristal acetate (UPA), a type of sPRL.
• Chemorepulsion was confirmed in rabbit and mouse spermatozoa, and diminished with non-capacitated sperm.

Conclusions:

• Human spermatozoa are capable of chemorepulsive behavior when capacitated.
• This repulsion from sPRL and zinc suggests a role in preventing polyspermy and understanding contraceptive mechanisms.
• Further research is needed to elucidate the molecular mechanisms underlying sperm chemorepulsion.