There are a variety of contraceptive methods for women, but only two methods for men: condoms and vasectomies. Both methods have drawbacks.
Some men are allergic to the latex in condoms. Vasectomies are difficult to reverse and can be painful.
One method currently being investigated is called nanocontraception, which is an alternative male contraceptive option.
An on/off switch.
The idea of delivering nanoparticles to the testicles is based on the idea that they can be warmed.
If you could warm up the testicles just a bit, you could turn sperm production on and off at will because the less fertile they become, the warmer they get. The testicles can be destroyed if they become too warm, and the tissue can no longer produce sperm, even when they return to their normal temperature.
The first study on using nanotechnology to warm testicles was done on mice. His first experiments involved injecting something into a mouse's testicles.
Imagine a tube of 120 gold atoms with a diameter of 30 gold atoms, coated with a few long polymer chains on their surface. They looked likebacteria with hairs sticking out.
The mice's testicles were then irradiated. The temperature of the nanoparticles was between 37 and 45 C.
Even though there was no reliable way to measure the pain of the procedure, it was assumed that it was painful for the animals. The researchers looked for other ways to inject the nanoparticles.
The rods are made of iron.
Sun's team published a paper in July of 2021. The new method of makingnanorods has the same size and shape as the earlier ones, but they are coated with a different type of acid.
The magnetic nanoparticles were injected into the mice's veins. A magnet was placed next to their testicles for four hours.
The procedure was done daily for four days.
An electric coil was wrapped around the testicles after the last day of treatment. The testicles were heated up by the magnetic field. Similar temperature increases were observed from a baseline of 29 C to between 37 and 42 C. The mouse's testicles became hotter the more days it had been injected.
After treatment, hotter testicles showed a gradual recovery, but fertility was down seven days after treatment.
There was no noticeable difference in the litter size of females impregnated by the treated mice and no defects were observed in the pups. The sperm that made it through seemed to be the same as before.
Sun and his colleagues found that the iron nanorods were completely eliminated from the body after being gradually eliminated from the testicles. The risk for long-term toxicity was reduced.
Many pet owners look for alternative methods of contraception because of the cost and irreversibility of surgical castration. Sun says that the method is already being used on cats in China, and that it is ready to be used on household pets.
David Powell, director of the Reproductive Management Center of the Association of Zoos and Aquariums in St. Louis, Mo., says that there is more interest in Europe in contraceptives than in North America.
Powell says there is not a big market for pet contraception in the US.
He says that contraception is not usually used with agricultural animals.
The agriculture industry is not doing much research on animal contraception because they are reared for consumption and slaughter.
Powell says that drug companies don't have a lot of motivation to make contraceptives for animals. The Reproductive Management Center collects data to evaluate how contraceptives work on different species.
One day, zoos could include contraceptives in their reproductive toolkit. Powell says further studies are needed to establish how painful it is and which species of iron can be used. Some mammals, such as rhinoceroses, may accumulate iron, which can be toxic in larger quantities.
The options are reversed.
Zoos often try to time breeding events over animals' life cycles, which could be a potential advantage of nanocontraception. It needs further study to find out how it can be reversed. All of Sun's experiments only treated mice once, and they were never injected with more nanoparticles after their testicles healed.
Sun admits that human contraception is still a long way off. Detailed studies will be required to prove that contraceptives are not harmful to men.
It is more difficult to put a man under anesthesia for four hours and wrap an electric coil around his testicles than it is to do the same thing on a mouse. Sun wants to be able to deliver the magnetic nanorods directly to the testicles.
It is not certain how many men will be comfortable with shrunken testicles, even if they recover their original size with time.
Get those condoms out.
Jeffrey Mo is a Global Journalism Fellow at the Dalla Lana School of Public Health.
The Conversation's article is a Creative Commons licensed one. The original article can be found here.
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