Analyzing alcohol and tobacco addiction from a genetic perspective
Genetic research has made monumental strides since its humble beginnings just over 150 years ago. Today, researchers have the technical ability to examine the human genome and evaluate DNA. Dr. Marissa Ehringer, Associate Professor of Integrative Physiology at the University of Colorado, Boulder is studying the genetics of addiction, primarily tobacco and alcohol disorders. Dr. Ehringer's goal is to understand why people develop addictions, tolerance, and how those suffering from addiction can be treated more effectively.
Dr. Ehringer runs genetic studies designed to identify many factors affecting addiction. She uses genotyping and DNA sequencing to map variation in DNA. This information is used to identify specific genetic factors that influence certain addictive behaviors. While focusing on human genetics, research is also conducted using molecular lab studies and mouse models to understand the idea of addiction as a whole.
The genes studied by Dr. Ehringer code for nicotonic acetylcholine receptors. Found throughout the body but concentrated heavily in the brain, these are proteins in the nervous system that signal for a muscle to contract upon being chemically stimulated. When functioning normally, acetylcholine, a neurotransmitter, binds to these sites. Acting as a "hijacker" of the same site, nicotine will also bind at these sites, ultimately leading to a change in their function. This leads to an increased tolerance to nicotine, raising the required intake needed to achieve the same effects. Dr. Ehringer and others have discovered that a person with this genetic risk variant smoke an average of one additional cigarette a day. When compiled over a long term this creates a significant increase in consumption and leads to risk for other diseases such as lung cancer.
Dr. Ehringer's laboratory uses laboratory approaches to study the function of genetic variants associated with addiction. For example, different versions of the DNA lead to differences in how the nicotinic receptor functions in the brain, or may lead to differences in how the gene is expressed.
Dr. Ehringer is using animal models to examine the effects of exercise on alcohol and nicotine consumption. There are strains of mice that will voluntarily consume alcohol, 70-80% of the time when given a two bottle (the other being water) choice, creating ideal natural candidates for a study of this design. In order to test the hypothesis that exercise and alcohol occupy the same areas of the brain independently, mice are organized into 4 different cage conditions. Two of these cages are "boring" with no running wheel, one with only water and the other with an alcohol/water choice. Two cages contain a running wheel, one with water, one with an alcohol/water choice. Dr. Ehringer has found that when given the option of the running wheel, the mice decreased their alcohol consumption to around 50%. This is significant because it indicates no preference, whereas any less would indicate an avoidance of alcohol.
In 2013 alcohol and tobacco consumption cost the American healthcare industry 126 billion dollars, according to government statistics. By understanding the impact alcohol and nicotine have on the human body and brain at the genetic level, we can not only reduce the burden of those costs, but also assist people in living a healthier lifestyle. Data on the genetics of addiction can be used to design more efficient and effective pharmacological treatments for those suffering from addiction. Knowing whether or not you have predisposed risk factors for consumption may also help with preventative measures for at-risk individuals.
As a senior at Indiana University, Dr. Ehringer had the opportunity to work alongside researchers in a university laboratory. It was there she realized she had a passion for genetics that had been growing since high school. This experience led her to pursue graduate school. Upon starting graduate school, the choice to study genetics came naturally, and by coincidence Dr. Ehringer fell under the advisory of researchers studying alcoholism and psychiatric genetics. This field is relatively understudied when compared to the genetics research of major diseases such as cancer or diabetes. However, since behavioral diseases increase the risk for a person to develop more serious disorders, the ability to research preventative and treatment strategies offered Dr. Ehringer the niche field of study that complemented all of her goals.
Though working as a researcher in the fields of biology and genetics, Dr. Ehringer has a second Bachelor's degree in French from Indiana University. Complementing her position as Associate Professor at CU Boulder. Dr. Ehringer is also a faculty fellow for the Institute for Behavioral Genetics, and a member of both the Center for Neuroscience and the University of Colorado Cancer Center, Lung/Head and Neck Program.
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