With a new target identified in sperm for contraception, men may one day take contraceptive pills.
Credit: Wikimedia
SYDNEY: Researchers have found the trigger that activates sperm to start them swimming, which could lead to a male contraceptive and also explain the link between marijuana use and sperm damage.
Proteins called Hv1 in the tails, or flagella, of sperm eject protons in response to alkaline conditions outside the cell, such as in the vagina, said a study published today in the journal Cell. This elevates the pH inside the sperm and activates the flagella for swimming.
Biophysicist and study author Yuriy Kirichok, from the University of California in San Francisco, said scientists have searched for a link between sperm activation and alkalinity since the early 1980s. However, Hv1 was not discovered until 2006.
Possible male contraceptive
"What we're very excited about is that we've found the molecule that elevates sperm intracellular pH and we've found how that molecule is activated," he said.
Sperm are unable to achieve fertilisation until they go through the activation process, said Kirichok. They remain in this quiescent state inside the male reproductive tract to avoid burning out.
According to Kirichok, Hv1 is an attractive target for research into male fertility because there will be cheap, reproducible methods to search for a compound to control Hv1 and sperm activation.
Hv1 gives sperm a jump start
Hv1 is easily introduced into human embryonic kidney cells, which are favoured by drugs companies because they are easy to culture and test in the lab.
The inside of the male reproductive tract is slightly acidic, with a pH of less than 6.5. This prevents Hv1 from ejecting protons.
Proton ejection starts when the pH outside the cell becomes alkaline, such as in the female reproductive tract. The loss of protons raises the pH inside sperm cells to above 6.5 and this activates their flagella, so they can move around, said Kirichok.
Once the pH inside the cell reaches 7.0 (neutral) it activates an influx of calcium into the sperm flagellum to cause hyperactivation of sperm motility. At this moment, the beating of the flagella is sufficiently accelerated to give sperm the strength to tunnel into the female ovum.
nonsense
The myth that marijuana somehow lowers fertility is total nonsense. This fear tactic has been perpetuated by the anti-marijuana lobby and has been proven to be circumstantial at best.
Your comment proves one
Your comment proves one thing for sure; chronic marijuana use causes stupidity.
Actually...
He's right, there's mixed evidence on the effects of marijuana on fertility. I've read reports where the opposite is observed. In fact, in the movie Super High Me, his sperm count actually went up after heavy use of marijuana. But I enjoyed how the idiot who commented 2nd just disregarded this as stupidity without refuting anything, that kid's going places *rolls eyes*
stupidity
Your comment actually made you sound more stupid than the first comment, which was not stupid at all. Smoke it or don't smoke it, your choice. Free the Weed.
Haha
Man this comment made me laugh. This right here is the problem. Health effects be damned! Americas real problem is sheep like this fool.
And sheep like the author of this article. God how misleading the word "link" can be. It's like saying chalk causes lung cancer because it's shaped like cigarettes. Just because the molecule is SIMILAR to the ones found in marijuana does NOT mean that it causes low fertility. The 'link' is that the molecules have similar structures but so does carbon monoxide (CO) and carbon dioxide (CO2). The only difference is ONE little extra oxygen atom, but the first will KILL you, the second is harmless and even produced by the body in (relatively) large quantities.
Want proof? They are not using ANY of the molecules found in marijuana smoke for this contraceptive. Not one. This new discovery has about as much to do with the reproductive harm caused by marijuana use as the positions of planets and stars in the galaxy can influence our lives (Astrology lol). But then again, this comment and the author of this article probably believe in that too.
Indeed
As the poster above me stated: this entire study was done using synthetic cannabinoids. Synthetic cannabinoids have a similar molecular structure to those in marijuana, but are absolutely not the same. Would you drink Hydrogen Peroxide (HO)? Of course not, and yet it's molecularly the same as water (H20) - minus one hydrogen atom.
So, what should we take from this?
Marijuana use has not been linked to lower fertility when looking at demographics and birth rates among users. What does that tell us? While marijuana may or may not effect how sperm swim, it's probably an acute effect that has no long term fertility consequences.
However, some synthetic cannabinoids have been shown to cause sperm to swim prematurely and die. This potentially could lead to a birth control method for men, but this is just the first step.
The aggression towards marijuana users is kind of silly. It's safer and less addictive than alcohol or tobacco.
H2O2,
Geez, weez, read yer peroxide label! It's water PLUS an Oxygen atom. 'N it probly won't hurt ya.
(signed) willird
well put
If "herb" caused any sort of infertility the country of Jamaca would have cested to exist long ago. So would have Amsterdam, San Francisco, heck, even the entire US would have had a population decrease of some sort. But that is not the case, poplulation has actually increased (globally even) as a whole.
did you read the article?
Although I'm not disputing there may be a link between marijuana usage and sperm motility (as this article hints), the actual research article did not make this claim (pg 330-331). To be specific, they found that the endocannabinoid anadamine (which is a cannabinoid produced by humans naturally, NOT by cannabis) affects sperm motility directly. They even tested whether inhibiting the CB1/CB2 receptors would mimic this effect and did not get any correlation ("probably caused by direct interaction of anandamide with HSPer channel)". Please stop with the sensationalist reporting, thanks.
Editor reply
Hi,
Thanks for reading our article and commenting.
The link between marijuana usage and reduced fertility in males is well established, please see this website for more information:
http://www.swedish.org/17062.cfm
Polina Lishko from the University of California in San Francisco, the lead author of the study, on the role of cannabinoid binding receptors CB1/CB2:
"While role of CB1/CB2 receptors in sperm motility is yet to be tested, the role of Hv1 in sperm motility is now defined. AEA [a cannabinoid produced by the human body] acts upon Hv1, not CB1/CB2 and therefore any cannabinoid will do the same, they will bind to Hv1 and rapidly activate sperm motility. Therefore I believe it is valid to suggest a link between cannabis alkaloids acting upon Hv1 and reduced sperm motility."