News | Scientists Discover Sperm ‘Energy Switch’ That Could Advance Male Contraception
Researchers at Michigan State University have discovered a molecular “switch” that controls bursts of energy in sperm, rapidly increasing their motility as they approach an egg. The researchers believe the finding could deepen understanding of fertilization and provide a new direction for developing safe, nonhormonal male contraceptives.
The findings were published in the Proceedings of the National Academy of Sciences (PNAS).
Sperm Experience an “Energy Burst” Before Fertilization
The team found that mammalian sperm are generally in a relatively low-energy state before ejaculation. Once inside the female reproductive tract, however, sperm rapidly undergo several changes, including:
A marked increase in swimming speed
Changes to the structure of the sperm’s outer membrane in preparation for binding to the egg
These changes require cells to substantially increase energy production over a short period.
Corresponding author Melanie Balbach, assistant professor in Michigan State University’s Department of Biochemistry and Molecular Biology, said: “Sperm metabolism is highly specialized. It is focused almost entirely on one goal—producing enough energy to achieve fertilization.”
She noted that many cells rapidly switch from low- to high-energy states under different conditions, making sperm an ideal model for studying this metabolic reprogramming.
Tracking How Sperm Use Glucose
To determine the source of the sperm energy burst, the team developed a method to track how sperm use glucose, an important fuel molecule.
Sperm absorb glucose from their surroundings and convert it into usable energy through a series of metabolic reactions. By labeling glucose molecules and tracking their metabolic pathways within cells, the researchers created a detailed map of sperm energy production.
Balbach compared the process to tracking a car’s route: “It’s like painting the roof of a car bright pink and then using a drone to follow it through traffic.”
She explained that in active sperm, the researchers observed the “labeled fuel” moving much faster through metabolic pathways and following specific routes to complete energy conversion.
The Key Enzyme Aldolase Drives Energy Release
The study found that an enzyme called Aldolase plays a key role in sperm energy metabolism. It helps break glucose down into molecules used to produce energy, supplying the power sperm need for rapid movement.
At the same time, sperm also draw on stored energy reserves when they become active. Other enzymes act like “traffic controllers,” regulating how fuel flows through different metabolic pathways and affecting the efficiency of energy production.
Using research resources including Michigan State University’s Mass Spectrometry and Metabolomics Core, the team ultimately mapped the multistep, high-energy metabolic process sperm require for fertilization.
A New Approach to Nonhormonal Male Contraception
The researchers said the finding has several implications for reproductive medicine.
About one in six people worldwide experience infertility. Studying sperm energy metabolism may help develop new diagnostic tools and improve assisted reproductive technology.
The discovery may also provide a new direction for male contraceptive development.
Balbach noted that much previous research on male contraception has focused on suppressing sperm production. This approach often has limitations, including a lack of immediate contraceptive effect, and many methods rely on hormonal intervention that may cause significant side effects.
In contrast, inhibiting sperm energy metabolism could temporarily reduce sperm function without affecting sperm production.
She said: “If we can safely target key enzymes that regulate sperm metabolism, it may be possible to develop a nonhormonal contraceptive that temporarily suppresses sperm function when needed.”
Expanding Reproductive Options for Men
The researchers believe that if future studies can apply this mechanism to human sperm, the strategy could give men more options for reproductive management.
Balbach said about half of pregnancies worldwide are currently unintended, making it important to expand male contraceptive options.
She said: “This could not only give men more agency in reproductive decisions but also reduce the side effects of contraception, which are currently borne mainly by women and often involve hormones.”
The team plans to continue investigating how sperm use different fuel sources, such as glucose and fructose, to meet their energy needs and to further validate these mechanisms in human sperm.
News | Scientists Discover Sperm ‘Energy Switch’ That Could Advance Male Contraception
News | Scientists Discover Sperm ‘Energy Switch’ That Could Advance Male Contraception
Researchers at Michigan State University have discovered a molecular “switch” that controls bursts of energy in sperm, rapidly increasing their motility as they approach an egg. The researchers believe the finding could deepen understanding of fertilization and provide a new direction for developing safe, nonhormonal male contraceptives.
The findings were published in the Proceedings of the National Academy of Sciences (PNAS).
Sperm Experience an “Energy Burst” Before Fertilization
The team found that mammalian sperm are generally in a relatively low-energy state before ejaculation. Once inside the female reproductive tract, however, sperm rapidly undergo several changes, including:
A marked increase in swimming speed
Changes to the structure of the sperm’s outer membrane in preparation for binding to the egg
These changes require cells to substantially increase energy production over a short period.
Corresponding author Melanie Balbach, assistant professor in Michigan State University’s Department of Biochemistry and Molecular Biology, said: “Sperm metabolism is highly specialized. It is focused almost entirely on one goal—producing enough energy to achieve fertilization.”
She noted that many cells rapidly switch from low- to high-energy states under different conditions, making sperm an ideal model for studying this metabolic reprogramming.
Tracking How Sperm Use Glucose
To determine the source of the sperm energy burst, the team developed a method to track how sperm use glucose, an important fuel molecule.
Sperm absorb glucose from their surroundings and convert it into usable energy through a series of metabolic reactions. By labeling glucose molecules and tracking their metabolic pathways within cells, the researchers created a detailed map of sperm energy production.
Balbach compared the process to tracking a car’s route: “It’s like painting the roof of a car bright pink and then using a drone to follow it through traffic.”
She explained that in active sperm, the researchers observed the “labeled fuel” moving much faster through metabolic pathways and following specific routes to complete energy conversion.
The Key Enzyme Aldolase Drives Energy Release
The study found that an enzyme called Aldolase plays a key role in sperm energy metabolism. It helps break glucose down into molecules used to produce energy, supplying the power sperm need for rapid movement.
At the same time, sperm also draw on stored energy reserves when they become active. Other enzymes act like “traffic controllers,” regulating how fuel flows through different metabolic pathways and affecting the efficiency of energy production.
Using research resources including Michigan State University’s Mass Spectrometry and Metabolomics Core, the team ultimately mapped the multistep, high-energy metabolic process sperm require for fertilization.
A New Approach to Nonhormonal Male Contraception
The researchers said the finding has several implications for reproductive medicine.
About one in six people worldwide experience infertility. Studying sperm energy metabolism may help develop new diagnostic tools and improve assisted reproductive technology.
The discovery may also provide a new direction for male contraceptive development.
Balbach noted that much previous research on male contraception has focused on suppressing sperm production. This approach often has limitations, including a lack of immediate contraceptive effect, and many methods rely on hormonal intervention that may cause significant side effects.
In contrast, inhibiting sperm energy metabolism could temporarily reduce sperm function without affecting sperm production.
She said: “If we can safely target key enzymes that regulate sperm metabolism, it may be possible to develop a nonhormonal contraceptive that temporarily suppresses sperm function when needed.”
Expanding Reproductive Options for Men
The researchers believe that if future studies can apply this mechanism to human sperm, the strategy could give men more options for reproductive management.
Balbach said about half of pregnancies worldwide are currently unintended, making it important to expand male contraceptive options.
She said: “This could not only give men more agency in reproductive decisions but also reduce the side effects of contraception, which are currently borne mainly by women and often involve hormones.”
The team plans to continue investigating how sperm use different fuel sources, such as glucose and fructose, to meet their energy needs and to further validate these mechanisms in human sperm.
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