The conception of a child is a highly complex process and many factors determine the viability of a pregnancy when conception occurs. Many couples are unable to conceive and about half the time, the barrier to conception lies within the male reproductive system. Many factors determine male fertility, including the health of sperm and semen. The exact mechanisms resulting in poor sperm quality have been elusive but a team of California physiologists may have discovered the key to unlocking the mystery of sperm-related male infertility.
Physiologist Melissa Miller presented the findings of her research team at the 58th Annual BiophysicalSociety Meeting in San Francisco, California, in February. She shares research laboratories with her colleagues at the University of California (UC) in Berkeley and San Francisco. According to Miller, “Any knowledge gained in this area may help create much-needed diagnostic testing and treatments for male infertility, which is, in essence, an idiopathic disease, because at this time 80% of male infertility cases can’t be diagnosed or treated.”
Miller’s team focused on ion channels considered crucial to sperm fertility. Ion channels are proteins that regulate the activity of certain elements within a sperm cell. Each of the three channels the team identified is responsible for regulation of one of three specific elements within sperm: calcium, potassium, and protons.
The ion channel for calcium is found in no other cell of the human body except the sperm. During spontaneous conception, the sperm cell turns on the ion channel to calcium when the sperm comes in contact with progesterone in the female reproductive tract. Once calcium ions become activated by progesterone exposure, sperm mobility kicks into action and it travels to the egg.
In sperm-related male infertility, the calcium ion channel does not become active in the presence of progesterone. With further study, the UC researchers hope to devise a diagnostic test for proper expression of the calcium ion channel and a therapeutic method for turning on the calcium ion channel when progesterone has no effect on it.
Dr. Yuriy Kirichok, a member of the UC research team, says certain medications can interfere with the calcium channel in a way that might contribute to male infertility. One family of drugs that raises Kirichok’s suspicions is the beta-channel blockers often prescribed for the treatment of cardiovascular diseases.
Other causes of male infertility can include semen quality, DNA damage that can be related to the aging process, and physical abnormalities of the male reproductive tract. Smoking has been linked to male infertility as well as obesity, drug and alcohol consumption, strenuous work-outs in high-impact sports, and exposure to excessive heat from environments such as hot tubs and saunas or holding a laptop computer too close to the groin.
Source: Miller, Melissa R. “Regulation of CatSper Channel Through Non-Conventional Lipid Signaling (presentation abstract).” Biophysical Society 58th Annual Meeting. Biophysical Society / Coe-Truman Technologies, Inc. n.d. Web. Mar 3, 2014.