A graduate student from Stony Brook University working under Brookhaven Laboratory, Carlos Bermeo said that since the association between drugs and the places where they are used can trigger craving and/or relapse in humans, a medication that could aid in the reduction or even extinction of such responses could be a powerful tool in the treatment of addiction.
The D-cycloserine was originally developed as an antibiotic. But this drug has also shown to extinguish conditioned fear in pre-clinical (animal) studies, and has been successfully tested in human clinical trials for the treatment of acrophobia or fear of heights. This finding led the researchers to wonder whether D-cycloserine could extinguish drug seeking behaviors as well. Last 2006, a group of scientists not associated with the Brookhaven Lab tested this hypothesis in rats. They found out that D-cycloserine facilitated the extinction of “cocaine conditioned place reference”-- in which the tendency for the animals to spend more time in a chamber where they had been trained to expect cocaine than in a chamber where they had no access to the drug whatsoever. This study builds on the previous work and adds information on the drug dose effect, the lasting properties of the treatment, and the locomotor effects of this compound.
In the study, the group worked with C57bL/c mice. The animals were first trained to receive cocaine in a specific environment. Once conditioned, place preference was established (animals willingly spent more time in a cocaine-paired environment than in a neutral environment), the mice were treated with either D-cycloserine or saline and were allowed to spend forty minutes in either the previously cocaine-paired environment in which the drug was no longer available, or the neutral environment. According to one of their researchers, this paradigm would be analogous to a clinical approach where the addict is returned to their natural environment where drug use was done, but this time with no drug available. He added that reduced seeking of the drug in the same environment—that is the extinction behavior—is a great indicator of future success in treatment and reduced chance of relapse.
However, these researchers said that it is important to remember that these are very preliminary results from a small animal study, and much further research will be required before testing this drug in humans. Nonetheless, it is inspiring to know that this drug may show promise in treating cocaine addiction that continues to take a toll on society and for which no pharmacological treatment currently exists. Such research studies would take us a step closer in treating phobias, as well as drug abuse.