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12 Nov 2004
Male monkeys that experienced a strong immune response after being injected with the protein eppin maintained the ability to copulate with female monkeys but did not impregnate any of them, a finding that could lead to the development of a new male contraceptive, according to a study published in the Nov. 12 issue of the journal Science, the Raleigh News & Observer reports.
Michael O'Rand of the University of North Carolina-Chapel Hill and colleagues in California and India injected nine male macaque monkeys with eppin, which is produced naturally in the testes and epididymis and attaches to sperm in the end stage of sperm development (Clabby, Raleigh News & Observer, 11/12).
After being injected with the protein, seven of the monkeys' bodies produced a strong immune response to the protein, and the antibodies attacked the eppin and disabled the sperm (Szabo, USA Today, 11/12).
All seven monkeys remained healthy and were able to copulate normally but were rendered infertile. However, when the researchers stopped administering the immunizations, five of the seven monkeys impregnated females (Raleigh News & Observer, 11/12).
The other two monkeys appeared to remain infertile following cessation of immunization. "We don't understand the exact mechanism yet, but we think the immunocontraception works by preventing the sperm from freeing itself from the seminal fluid to make its way to the uterus and oviducts to fertilize the eggs," O'Rand said (Detroit Free Press, 11/12).
Other Prospective Male Contraceptives
Although it is unclear whether such immunizations would produce the same results in humans, the research offers hope that a male contraceptive could be developed using immunocontraception, the News & Observer reports (Raleigh News & Observer, 11/12).
So far, research on developing a male contraceptive has focused on reducing male hormones and sperm production, the Detroit Free Press reports (Detroit Free Press, 11/12).
While a hormonal injection could prevent men from being able to impregnate their partners, the injections eliminate sperm production and dampen sex drive and would have to be taken in combination with testosterone (Raleigh News & Observer, 11/12).
However, trials of experimental hormonal male contraceptives are ongoing, and such male contraceptives are closer to reaching the market than an immunocontraceptive injection, the AP/CBSNews.com reports (Schmid, AP/CBSNews.com, 11/11). O'Rand said that research and trials on the injection could take 10 years (Washington Post, 11/12).
Challenges
Regardless of which male contraceptive becomes available first, one of the "greatest challenges" to its success will be psychological, Susan Benoff, former president of the Society for Male Reproduction and Urology, said.
Many women have become used to being the person responsible for preventing pregnancy and might not trust men to take a pill or receive an injection. "If you are the woman, you are the one who's going to be pushing out the eight-pound bowling ball, so you really have to trust that he's going to do what he says he's going to do," Benoff said. In addition, many men prefer condoms, which are inexpensive, widely available and protect against sexually transmitted diseases, according to USA Today (USA Today, 11/12).
http://www.kaisernetwork.org
Male monkeys that experienced a strong immune response after being injected with the protein eppin maintained the ability to copulate with female monkeys but did not impregnate any of them, a finding that could lead to the development of a new male contraceptive, according to a study published in the Nov. 12 issue of the journal Science, the Raleigh News & Observer reports.
Michael O'Rand of the University of North Carolina-Chapel Hill and colleagues in California and India injected nine male macaque monkeys with eppin, which is produced naturally in the testes and epididymis and attaches to sperm in the end stage of sperm development (Clabby, Raleigh News & Observer, 11/12).
After being injected with the protein, seven of the monkeys' bodies produced a strong immune response to the protein, and the antibodies attacked the eppin and disabled the sperm (Szabo, USA Today, 11/12).
All seven monkeys remained healthy and were able to copulate normally but were rendered infertile. However, when the researchers stopped administering the immunizations, five of the seven monkeys impregnated females (Raleigh News & Observer, 11/12).
The other two monkeys appeared to remain infertile following cessation of immunization. "We don't understand the exact mechanism yet, but we think the immunocontraception works by preventing the sperm from freeing itself from the seminal fluid to make its way to the uterus and oviducts to fertilize the eggs," O'Rand said (Detroit Free Press, 11/12).
Other Prospective Male Contraceptives
Although it is unclear whether such immunizations would produce the same results in humans, the research offers hope that a male contraceptive could be developed using immunocontraception, the News & Observer reports (Raleigh News & Observer, 11/12).
So far, research on developing a male contraceptive has focused on reducing male hormones and sperm production, the Detroit Free Press reports (Detroit Free Press, 11/12).
While a hormonal injection could prevent men from being able to impregnate their partners, the injections eliminate sperm production and dampen sex drive and would have to be taken in combination with testosterone (Raleigh News & Observer, 11/12).
However, trials of experimental hormonal male contraceptives are ongoing, and such male contraceptives are closer to reaching the market than an immunocontraceptive injection, the AP/CBSNews.com reports (Schmid, AP/CBSNews.com, 11/11). O'Rand said that research and trials on the injection could take 10 years (Washington Post, 11/12).
Challenges
Regardless of which male contraceptive becomes available first, one of the "greatest challenges" to its success will be psychological, Susan Benoff, former president of the Society for Male Reproduction and Urology, said.
Many women have become used to being the person responsible for preventing pregnancy and might not trust men to take a pill or receive an injection. "If you are the woman, you are the one who's going to be pushing out the eight-pound bowling ball, so you really have to trust that he's going to do what he says he's going to do," Benoff said. In addition, many men prefer condoms, which are inexpensive, widely available and protect against sexually transmitted diseases, according to USA Today (USA Today, 11/12).
http://www.kaisernetwork.org
