OPRM1 A118G SNP, Alcohol Response, and Striatal Dopamine

This study will examine the relationship between variations in a gene called OPRM1 and the response to alcohol. The OPRM1 (Mu-opioid Receptor-1) gene helps regulate brain pathways involved in experiencing pleasure. Brain pathways use a chemical called dopamine. Different forms of the OPRM1 gene may lead to differences in how dopamine is released and subsequently to differences in a person's response to alcohol. Healthy non-smokers between 21 and 45 years of age may be eligible for this study. Candidates are screened with a medical and psychiatric history and physical examination, blood and urine tests, and breathalyzer (breath alcohol test). A blood test is also done to determine the variant of OPRM1 gene. Participants undergo the following procedures in three study sessions: Session 1 " Breathalyzer test, urine test for illicit drugs and pregnancy test for women who can become pregnant. " Insertion of catheters (plastic tubes) into a vein in one arm for infusing alcohol and into the other arm for drawing blood samples. " Completion of questionnaires on how intoxicated the subject feels. " Blood draw for research studies. " Eye movement test (a visor with a digital camera tracks the subject's eye movements while he or she watches lights on a computer screen). " 45-minute alcohol infusion (up to 0,08 grams per deciliter - a level considered in most states as driving under the influence of alcohol). " Repeat breathalyzer, questionnaires, eye movement test and blood draw every 15 minutes during the infusion and again after the infusion is complete. " Subjects remain in the clinic until their blood alcohol content falls below 0.02 g/dL, determined by a breathalyzer test done every 15 minutes. Subjects can usually return home about 3 to 4 hours after the alcohol infusion stops. Sessions 2 and 3 The procedure is the same as for session 1, except subjects receive an infusion of alcohol one session and an infusion of saline (salt water) the other. Also, subject