Effects of Nicotine on Brain Opioid Receptors

• Status: Terminated
• Trial end date: 2011-03-01
• Target enrollment: 0
• Participant gender: All

Summary

A substantial body of evidence implicates the endogenous opioid system, and the mu opioid receptor (MOR) in particular, in the reinforcing effects of drugs of abuse, including nicotine. A single nucleotide polymorphism (SNP) in the mu opioid receptor gene (OPRM1 Asp40) is associated with the ability to quit smoking, as well as nicotine reward and withdrawal symptoms. However, the precise mechanism through which this SNP influences nicotine dependence remains unresolved. This positron emission tomography (PET) study will examine whether this OPRM1 SNP alters MOR binding in response to nicotine in human smokers. Specifically, we will use [11 C]carfentanil PET imaging to assess the effects of intravenous (IV) nicotine versus saline (within-subject) on MOR binding potential in 24 chronic smokers genotyped prospectively and stratified by OPRM1 genotype.

• Accepts Healthy Volunteers?: Accepts Healthy Volunteers

Details

• Lead Sponsor: University of Pennsylvania
• Collaborator: National Institute on Drug Abuse (NIDA)
• Treatments: Nicotine

Criteria

Inclusion Criteria:

• Non-treatment seeking smokers of European ancestry

• Between 18 and 50 years old

• Smoking at least 10 cigarettes per day for at least the past 6 months

• Able to provide informed consent

• Fluent, English-speaking

• Weight ≤ 300 lbs.

Exclusion Criteria:

• Current enrollment or plans to enroll in a smoking cessation program, or use other smoking cessation medications in the next 2 months

• Provide a Carbon Monoxide reading of ≤10 ppm at Medical screening.

• History of substance abuse and/or currently receiving treatment for substance abuse (e.g., alcohol, opioids, cocaine, marijuana, or stimulants)

• Current alcohol consumption that exceeds 25 standard drinks/week

• Providing a breath alcohol concentration (BAC) reading of > 0.01 at any session.

• Women who are pregnant, planning a pregnancy, or lactating; all female subjects shall undergo a urine pregnancy test at each session

• Women of child-bearing age must agree in writing to use an approved method of contraception

• History or current diagnosis of psychosis, major current depression or bipolar disorder, ADHD, schizophrenia, or any Axis 1 disorder as identified by the MINI

• Serious or unstable disease within the past 6 months (e.g., cancer [except melanoma], heart disease, HIV)

• History of epilepsy or a seizure disorder

• History or current diagnosis (last 6-months) of abnormal rhythms and/or tachycardia (>100 beats/minute); history or current diagnosis of COPD, cardiovascular disease (stroke, angina, coronary heart disease), heart attack in the last 6 months, uncontrolled hypertension (SBP>150 or DBP>90)

• Any medical or neurological condition that might interfere with the distribution of the radiotracer as determined by the study MD

• Current or past use (within past 12 months) of any medications containing naltrexone or other MOR antagonists (e.g., Revia, Trexan)

• Current use or recent discontinuation (within last 14-days) of the following medications

• Any form of smoking cessation medication (Zyban, Wellbutrin, Wellbutrin SR, Chantix, NRT)

• Recent (within last 2 weeks) or planned use of psychotropic medications (anti-psychotics, anti-depressants (tricyclic, SSRI, MAOI), anti-anxiety or panic medications, and stimulants (e.g., Provigil, Ritalin), and opiate-containing medications for chronic pain

• Allergic response to any form of opioids or naloxone

• Participants shall be instructed to refrain from using any study prohibited drugs (note - participants are allowed to take prescription medicines not in the exclusion list) throughout their participation in the study.

• Self-reported history of head trauma or prior seizure, brain (or CNS) tumor

• Self-reported history of claustrophobia (contraindicated for PET)

• Inability to complete the baseline study procedures within four hours and/or correctly, as determined by the principal investigator.