The End of Addiction
For the past four years, UCI Neuropharmacology professor, Olivier Civelli and postdoctoral scholar, Shinjae Chung have been experimenting with a process to control addiction.
While it is being praised as a potential cure for cocaine addiction, at the moment it may also eventually serve other purposes such as an anti-psychotic for schizophrenia or a drug to control food-consumption.
The Office of National Drug Control Policy approximates that 33.7 million Americans ages 12 and older have tried cocaine at least once in their lifetimes.
Although these statistics are relatively low compared to the number of deaths causes by other substances, cocaine addicts nonetheless find it difficult to stay off the drug and relapse is the primary reason addicts cannot quit.
Dopamine is a neurotransmitter located in the central nervous system that has a correlation with pleasure, which can be caused by eating, having sex, or taking drugs.
Cocaine addicts have a high level of melanin-concentrating hormone (MCH) in their brains which works in conjunction with dopamine.
UCI researchers found that the injection of a substance that blocks MCH would then regulate the level of cravings in the brain for cocaine to prevent relapse.
Chung said that no one was really sure how MCH affected the brain.
In fact, it was initially thought that blocking MCH would change more subtle addictions such as food cravings.
“People were hoping that this system would stop obesity and overeating,” she said.
The history of the system is also surprising. In 1983, the MCH peptide was discovered by a scientist who was examining the way that certain fish change colors to avoid predators.
Some of the fish would release a peptide that would make their skin lighten and a different peptide would darken it. The peptides had no affect on human skin but did have some interesting results.
The darker peptide, scientists seemed to increase food intake and the peptide that sparked a light color change would seemed to lead to a decrease in food intake.
However, after tests, they came to the conclusion that there was no correlation between food intake and MCH which is when they began to test it with drug dependency.
The experiment involved isolated rats that were trained for cocaine. The rat became addicted to the substance (which was always distributed when a light shined on the rat) and wanted more.
Chung then injected the MCH blocking chemical into the rats’ brains and used light to trigger relapse, since the rat associated the light with cocaine.
Once the chemical had been injected into the brains, the results showed that there was a significant drop in cravings for cocaine.
There is no current progress of the antagonistic substance within human medicine and it has never even been tested on humans.
“Pharmaceutical companies would have to modify the compound so it could be taken by mouth or injected somewhere else,” said Civelli.
However, the experiment was a breakthrough and was the first to show any association between an addictive nature to cocaine and how MCH and dopamine affect the brain’s nervous system.
Other uses of the MCH blocking discovery have been mentioned.
Chung and Civelli both said that regulating the dopamine system is important because it can also regulate schizophrenia, which is caused by an excess of dopamine.
Perfecting and blocking the system would create a new and different anti-psychotic.
“There is a part where the dopamine receptors work on locomotion and another part that regulates reward,” Civelli said, “the MCH system works on reward but not on locomotion (and that is what we would like to do.) With this, we could do something that works on anti-psychotic symptoms.”
Several projects related to drug abuse and addiction are being conducted on the UCI campus however, the system is extremely regulated.
“Every amount of drug related substance we get comes from the pharmacy,” Civelli said. “I have to sign for it, every amount needs to be recorded; it is always stored in a safe. If the cocaine ever disappeared, that would be a bad day in my life.”
“What we have is not a drug; we study a system that could do something for cocaine addiction. To my understanding the only treatment for cocaine addiction is not taking it,” Civelli said.