Two chemicals found in anti-fertility folk medicines block a key step in fertilization – the meeting of egg and sperm – and may make effective alternatives to today’s hormone-based contraceptives, which sometimes cause side effects.
The chemicals are effective at low doses that seem to have no adverse effect on egg or sperm, other than to prevent the sperm from pushing through the cells that congregate around the egg and an enveloping membrane called the zona pelucida.
compounds block hyperactivation in sperm
Compounds extracted from two plants, thunder god vine and aloe, prevent hyperactivation in sperm, the power kick necessary to fertilize the egg. The compounds are potential emergency contraceptives. Polina Lishko graphic.
They work by stopping sperm’s power kick, which is normally stimulated by the hormone progesterone secreted by cells surrounding the egg and makes the sperm’s tail whip forcefully to propel it toward and into the egg.
The chemicals could serve as an emergency contraceptive taken either before or after intercourse, or as a permanent contraceptive via a skin patch or vaginal ring, say researchers at the University of California, Berkeley. Human sperm take about five to six hours to mature once they enter the female reproductive system, which is enough time for the drug to enter the system and block the kick.
Also, because the chemicals prevent fertilization, they may be a more acceptable alternative in the eyes of those who object to emergency contraceptives, such as Plan B, that prevent the implantation of a potentially viable fertilized egg.
“Because these two plant compounds block fertilization at very, very low concentrations – about 10 times lower than levels of levonorgestrel in Plan B – they could be a new generation of emergency contraceptive we nicknamed ‘molecular condoms,’” said Polina Lishko, an assistant professor of molecular and cell biology, who led the team that discovered the anti-fertility properties of the two chemicals. “If one can use a plant-derived, non-toxic, non-hormonal compound in lesser concentration to prevent fertilization in the first place, it could potentially be a better option.”
Lishko, first author Nadja Mannowetz, a project scientist, and former postdoctoral fellow Melissa Miller will report their findings online this week in the journal Proceedings of the National Academy of Sciences.
Sperm’s power kick
Lishko and her lab colleagues study male and female reproduction, including the hormones that trigger hyperactivity in sperm. Sperm swim upstream in the reproductive track toward the egg using their tail, which normally moves with a steady, rhythmic motion. However, once sperm reach the egg and its protective cluster of cells, their tails switch to a whiplike motion, a power kick that gets the sperm through the scrum and into the egg. The key to this power kick is a calcium channel, called CatSper; when opened, calcium floods the tail, triggering the forceful tail snaps.
Polina Lishko and her lab colleagues study the hormones and other chemicals that regulate fertilization of the egg by sperm.
“The massive influx of calcium into the sperm tail changes the sperm tail’s beating pattern, making it highly asymmetrical,” Mannowetz said. “This asymmetrical bending gives the sperm cell enough force to drill through the tenacious egg vestment.”
Last year, the three researchers found that the hormone progesterone is key to opening the calcium channel and triggering tail whipping. The hormone binds to a protein called ABHD2, which in turn opens the channel. They began a search for other chemicals that would bind to ABHD2, either opening the channel, like progesterone, or blocking the channel.
In the new study, Mannowetz tested three other hormones: testosterone, estrogen and cortisol, a stress hormone. All three competed with progesterone and blocked tail whipping, though only testosterone and cortisol were effective at levels typical of the hormones’ levels in the body. This suggests, she said, that stress and high testosterone levels in women decrease fertility in part by preventing sperm from penetrating the egg.
They also found a second hormone that triggers tail whipping: a steroid structurally similar to progesterone called pregnenolone sulfate.
Purusing books on natural contraceptives used by indigenous peoples around the world, they came across several non-steroid chemicals isolated from anti-fertility plants that resembled the steroids that bind to ABHD2 and block CatSper. One of these was pristimerin, from the plant Tripterygium wilfordii, also known as “thunder god vine.” Leaves from the plant have been used as an antifertility drug in Chinese traditional medicine, though some compounds in the leaves are poisonous. It has also been used as a folk remedy for rheumatoid arthritis.
The other chemical was lupeol, which is found in plants such as mango and dandelion root. While it has been tested as an anticancer agent, it was not suspected of having contraceptive properties.
Mannowetz found that both pristimerin and lupeol blocked progesterone binding to ADHD2, preventing sperm’s power kick.
“These compounds not only blocked calcium channel activation, but also blocked sperm hyperactivated motility, reducing their activity to the level of nonactivated sperm cells,” Lishko said. “It doesn’t kill sperm basal motility. It is not toxic to sperm cells; they still can move. But they cannot develop this powerful stroke, because this whole activation pathway is shut down.”
Lishko and her colleagues are now working with researchers in Oregon to test how effective these chemicals are in preventing primate in vitro fertilization, since their own studies involved human sperm only. They also are searching for an inexpensive source of the chemicals, members of a family called triterpenoids, since concentrations in wild plants are too low for cost-effective extraction.
I am now 72 years old, and I had a vasectomy when I was only 25 years old. I have never regretted it. The birthrate in Occident is at the lowest in recorded history. From 2000 to present, the fertility rate declined 20%. Childlessness has risen across all racial and ethnic groups. A quarter of Occidental women end their childbearing years maternity-free.
The decision to have a child or not is a private one, but it takes place in Occident, in a culture that often equates womanhood with motherhood. Any discussion about the struggle to reconcile womanhood with modernity tends to begin and end with one subject: parenting.
What to expect when no one’s expecting? It reduces the number of consumers and taxpayers, but it increases the quality of life. Persons who choose not to become parents are finding new paths of acceptance. As their ranks rise, so do positive attitudes about leading a life in which having it all doesn’t mean having a baby.
Stupid legislatures have passed stupid anti-abortion resolutions, asking the public to decide whether the state constitution should define life as beginning at conception! The stupid resolutions mainly state the inalienable right to life of every human being at any stage of development must be recognized and defended.
Pro-choice activists criticize the new anti-abortion laws, arguing that they violate the US Supreme Court’s 1973 Roe v. Wade decision, which legalized abortions until the fetus is considered viable, at around 22-24 weeks into a pregnancy. Treating humans as livestock, stupid legislators, who introduced the stupid personhood resolutions, point out that the main purpose of them is to be a direct challenge to Roe v. Wade.
90% of people agree on the abortion of embryo, and 60% agree on the abortion of fetus. Embryo refers to the early stages of development within the womb, in humans up to the end of the second month. Fetus refers to the later stages of development when the body structures are in the recognizable form of its kind, in humans after the end of the second month of gestation.
Ayn Rand points out the capacity to procreate is merely a potential which man is not obligated to actualize. The choice to have children or not is morally optional. Nature endows man with a variety of potentials, and it is his mind that must decide which capacities he chooses to exercise, according to his own hierarchy of rational goals and values.
The mere fact that man has the capacity to kill, does not mean that it is his duty to become a murderer; in the same way, the mere fact that man has the capacity to procreate, does not mean that it is his duty to commit spiritual suicide by making procreation his primary goal and turning himself into livestock.
To an animal, the rearing of its young is a matter of temporary cycles. To man, it is a lifelong responsibility, a grave responsibility that must not be undertaken causelessly, thoughtlessly or accidentally.
In regard to the moral aspects of birth control, the primary right involved is not the right of an unborn child, nor of the family, nor of society, nor of God. The primary right is one which, in today’s public clamor on the subject, few, if any, voices have had the courage to uphold: the right of man and woman to their own life and happiness, the right not to be regarded as the means to any end.
Rand notes the task of raising a child is a tremendous, lifelong responsibility, which no one should undertake unwittingly or unwillingly. Procreation is not a duty, human beings are not livestock. For conscientious persons, an unwanted pregnancy is a disaster; to oppose its termination is to advocate sacrifice, not for the sake of anyone’s benefit, but for the sake of misery qua misery, for the sake of forbidding happiness and fulfillment to living human beings.
The human construct is open to wide interpretation. The dogma that life begins at conception is an utterly false assertion on its face because spermatozoa and ova cells are vibrantly alive long before they meet. Life most assuredly does not begin at conception. There are no discontinuities here as life just persists and inexorably continues and matures.