Despite those "amazing" cases of male pregnancyreported in the checkout-counter tabloids, the factremains that only women bear children. What's more,women bear most of the brunt of not bearing children _contraception.
A special section on "Reproduction: NewDevelopments," in this week's Science, (Dec. 2) notesthat "In the last 20 years, we've had no [fundamentally]new type of contraceptive." That's a quote from someonewho should know: Nancy Alexander, head ofcontraceptive development in the National Institute ofChild Health and Human Development.
And despite the prevailing respect for gender correctness,observes the Science section, "In contraception as inmany other facets of modern life, true gender equality isstill some ways off." Its author, Peter Aldhous, a staffwriter on the British journal New Scientist, points outthat: "Women worldwide take contraceptive pills, getfitted with intrauterine devices, and use a range of barriermethods to prevent pregnancy. But when it comes tomale contraceptives, it's the good old-fashioned condom .. . or nothing."
This will change if biochemist Rosemary Thau and otherresearchers of a male contraceptive vaccine aresuccessful. Thau directs contraceptive development at thePopulation Council in New York.
"In men," Science reports, "the focus is on reproductivehormones and sperm, and two vaccines have reached thestage of safety trials in human volunteers." Thau'sversion raises antibodies to gonadotropin-releasinghormone, which stimulates production of testosterone andof sperm.
Testosterone stimulates prostate tumors to grow, soprostate-cancer patients are receiving the PopulationCouncil testosterone-blocking antibody as a safety test ofits contraceptive efficacy. Aldhous observes that thisvaccine's side-effect, loss of libido, may be acceptable forcancer therapy "but probably not for a contraceptive."
Another antibody target, follicle-stimulating hormone,(FSH) avoids the libido factor. FSH also promotesproduction of sperm, but not of testosterone. Monkeysimmunized with a sheep-FSH-based vaccine at the IndianInstitute of Science in Bangalore experienced "arelatively long-lasting but reversible period of infertility."Human trials are under way.
Meanwhile, at the University of Connecticut inFramington, the husband-and-wife team of PaulPrimakoff and Diana Myles is targeting the spermatozoonitself, rather than systemic hormones that animate it.Their target for immunization is a sperm antigen, fertilin,now under development.
Aldhous concludes, "If approaches like that aresuccessful, it could begin to bring equality between menand women one step closer _ at least in the field ofcontraception." n
-- David N. Leff Science Editor
(c) 1997 American Health Consultants. All rights reserved.