Depending on the report or study, statistics show anywhere from twenty-five to seventy five percent of cases of male infertility cannot be adequately diagnosed or treated. Traditional evaluation including semen analysis, hormonal and or genetic testing and male genital imaging may result in an incomplete explanation as to the severity of deficits of sperm production. Any new information in this area could lead to the development of (needed) new diagnostic testing and treatment options for Male infertility.
A recent report by Miller et all, from UC, Berkeley and UC SF at the 58th Annual Biophysical Society Meeting, this past February (2014) has explored the role of sperm ion channels. These channels are located in the sperm cell membrane and may have a role in sperm function.
The report focused on three ion channels: “CatSper”, “Slo1” and Hv1. These channels regulate the flow of Calcium, potassium and protons, respectively. Historically the most well studied channel is CatSper which appears as an ion channel, solely on sperm cells.
Miller and others demonstrated that the female hormone progesterone activates CatSper. They also report that a lack of CatSper activity shows correlation to male infertility.
Prior to fertilizing an egg, a sperm has to go through several changes within the female reproductive tract. This includes an elevation of calcium within the cell as well as a cell membrane hyperpolarization largely regulated by potassium. Slo1 has been reported by other investigators to be the principal potassium ion channel in sperm.
Separately, Mannowetz et al reported (elife, October 2013) that progesterone inhibits Slo1 channels located on the sperm tail which may also lead to opening CatSper channels and raising both intracellular calcium and potassium. These are steps in “hyperactivation:, a component of sperm maturation which occurs prior to a sperm fertilizing an egg.
Hv1 is also confined to the sperm tail or flagellum or tail. Hv1 transports protons outside the cell and also works with CatSper to increase intracellular pH and calcium.
The study of these channels may make future diagnostic tests and therapies available. Sperm memberane channel dysfunction may offer explanations of male infertility, previously undiagnosed. Investigations are underway to explore manipulation of these channels both to improve male fertility as well as to possibly provide new methods for male contraception.
