Experts in drug addiction have long known that stress is often a predictor for relapse in recovered drug addicts and for usage in those currently using drugs. Many individuals turn to drugs when stress intensifies and believe that they are better able to cope in the short run.
Scientists hope to discover the specific brain functions related to how the brain processes stress. They are also trying to understand the use of drugs to mediate stress in order to develop effective medications for treating both stress and the brain response that leads to drug use as a remedy for stress.
Researchers in St. Louis and Seattle teamed up to explore the ways that stress affects mood and motivation for drugs. They discovered that blocking the stress cascade in brain cells may help reduce stress and in turn, reduce the anxiety, depression and need for drugs that occur when stress intensifies. The results of the study are printed in the August 11 issue of the journal Neuron.
The researchers found that when mice are exposed to stress, a protein in the brain called p38a mitogen-activated protein kinase (MAPK) is activated and changes the animal’s behavior. The mouse exhibits depression-like symptoms and is at a higher risk for addiction-related behaviors.
The research was conducted by a team comprised of researchers at Washington University School of Medicine in St. Louis and the University of Washington in Seattle. The first author for the study is Michael R. Bruchas, PhD., an assistant professor of anesthesiology and of anatomy and neurobiology at Washington University in St. Louis.
Effects of Stress
When exposed to stress, the mice activated the p38a MAPK, which lowers serotonin levels and triggers depression-like behavior, and causes the mouse to seek out drugs. The stressed animals also withdrew and ceased interaction with the other mice. In the mice that had earlier received cocaine injections in a specific place in their cages, the introduction of stress caused them to seek out the locations where the drug had been given earlier.
Bruchas explains that while the mice can’t verbalize their experiences or feelings, they exhibit behaviors that are similar to those found in humans who can describe their situations as symptoms of depression or a need for an addictive drug.
The scientists are hopeful that these new insights into the stress reactions that lead to depression and drug-seeking behavior may provide necessary tools for developing pharmaceutical treatment options for stress, depression and drug addiction.