Antiheroin vaccine successfully tested on rats

A vaccine will save you from heroin addiction

Nadezhda Markina, Newspaper.Roo 

Scientists were able to neutralize the drug on the same principle as a bacterium or virus. They managed to incite the immune system to heroin and so far get rid of drug addiction of rats. The queue is behind the person.

The treatment of drug addiction by vaccination is a new approach that is being actively developed at The Scripps Research Institute, USA. Specialists are developing vaccines against several addictive substances at once, and vaccines against cocaine and nicotine are already undergoing clinical trials, and a vaccine against methamphetamine is almost ready for clinical trials. The vaccine against heroin, which is discussed in the article Schlosburg et al. Dynamic vaccine blocks relapse to compulsive intake of heroin, published in the journal Proceedings of the National Academy of Sciences (see the popular retelling in the press release Preclinical Study Shows Heroin Vaccine Blocks Relapse – VM), has successfully passed preclinical animal studies.

Anti–drug vaccines, like all vaccines, should stimulate the immune system's response - the formation of antibodies against narcotic substances. But in this case there is a big difficulty that needs to be overcome somehow: the molecules of most of these substances are too small and simply arranged to cause a noticeable response of the immune system. Scientists from the Scripps Institution have managed to solve this problem: they have attached key fragments of the drug molecule (antigens) to large proteins that can trigger a powerful immune response. The vaccine against heroin is also arranged in the same way.

Heroin addiction is one of the most dangerous, currently it affects about 10 million people worldwide. However, there is another problem with heroin. After its injection into the blood, it decomposes very quickly to form 6-acetylmorphine and morphine. "Heroin metabolizes very quickly and turns into another substance called 6-acetylmorphine, which overcomes the barrier between the blood and the brain and enters the brain. It is this substance that causes the main effect of injecting heroin," explains Kim Janda, head of the laboratory.

Starting work on a heroin vaccine three years ago, a group of researchers in the laboratories of George F. Koob and Kim Jand set a task: the vaccine should bind not only heroin, but also its metabolites. To do this, it contains protein-bound antigens of heroin, 6-acetylmorphine and morphine.

The first animal trials of the vaccine, published in 2011, showed that it blocks some of the effects of heroin, such as pain relief. However, it was much more important to show how the vaccine acts on addiction and dependence on the drug. In a new study, scientists conducted appropriate testing on rats.

Rats were trained to heroin according to the well–known "self-stimulation" model: they were trained to press a lever to inject themselves with a dose - every three clicks caused an injection of heroin into a vein. The rats, accustomed to the drug, furiously worked the lever, then the injections stopped and the heroin no longer arrived. In such a situation, the rats experienced "withdrawal" and first pressed the lever, and then stopped. But if they were given at least one injection of heroin after a break, drug-dependent behavior immediately resumed. However, those animals to which the researchers injected the antiheroin vaccine did not succumb to the provocation and after the injection of the drug did not rush to the lever for an additive.

The results of another test are even more impressive. The rats developed a very severe heroin addiction, and they, working with a lever, injected themselves with a dose fatal to ordinary animals. Then they were deprived of the drug for 30 days. After that, some rats were injected with a real vaccine, and others with an imitation, dummy. After one shot of heroin, the placebo-trained rats rushed to the lever in search of the drug, and the vaccinated rats resisted the temptation.

"Heroin–addicted rats deprived of the drug will tend to get it again and again if it is made available, but our vaccine has stopped this behavior," comments George Koob. The researchers emphasize that the conditions of the experiment are similar to those in which a person with drug addiction finds himself. If he receives a dose after abstinence, it will immediately encourage him to actively search for a drug. The vaccine was able to break this vicious circle. "In general, we were able to stop them from entering the cycle of heroin consumption," said Joel Schlosburg, the first author of the work.

Studies have confirmed that the vaccine, stimulating the immune response, isolates heroin and its metabolites in the bloodstream, not letting them into the brain. Moreover, what is very important, it does not block the effect of methadone, buprenorphine and other opioid drugs that are usually used in substitution therapy. The fact is that the vaccine does not affect the opioid system as such at all, so it can be given to heroin addicts and at the same time continue to treat them with standard methods. The vaccine does not interfere with the action of drugs – opioid analgesics.

Scientists suggest that when switching to human trials, the effect of the vaccine will change somewhat, but in principle it should work the same way. Now they are looking for pharmaceutical companies that could finance clinical trials, and they expect that they will be successful. If the vaccine performs as well in clinical trials, it may become a standard treatment for heroin addiction, the authors of the experiment believe.

Portal "Eternal youth" http://vechnayamolodost.ru 07.05.2013