Serotonin 1B receptor imaging in pathological gambling

Abstract

Objectives. Although serotonergic mechanisms have been implicated in pathological gambling (PG), no ligand-based imaging studies have assessed serotonin receptors in individuals with PG. Given its role in substance addictions and its abundance in brain regions implicated in PG, we evaluated serotonin 1B receptors (5-HT_1BRs) in PG. Methods. Ten medication-free subjects with PG (mean ± SD age = 36.3 ± 9.4 years, nine men) and ten control comparison (CC) subjects (mean ± SD age = 35.8 ± 9.9 years, nine men) underwent [¹¹C]P943 positron emission scanning on a high resolution research tomograph. Results. 5-HT_1BR BP_ND values were similar in PG and CC subjects (P > 0.1). Among PG subjects, scores on the South Oaks Gambling Screen (SOGS) correlated positively with 5-HT_1BR BP_ND values in the ventral striatum (r = 0.66; P = 0.04), putamen (r = 0.67; P = 0.03) and anterior cingulate cortex (r = 0.73; P = 0.02). Conclusions. These findings provide the first evidence that PG severity in humans is linked to increased levels of 5-HT_1BRs in regions previously implicated in functional neuroimaging studies of PG. These findings indicate a potential role for serotonergic function in the ventral striatum and anterior cingulate cortex contributing to problem gambling severity and warrant further studies to investigate whether numbers of available 5-HT_1BRs might represent a vulnerability factor for PG or develop in relationship to problem gambling.

Key words::

• Pathological gambling
• brain imaging
• serotonin 1B receptor
• positron emission tomography
• South Oaks Gambling Screen

Acknowledgements

Support was provided by the following Grants: National Institutes of Health grants R21 AA018329, RL1 AA017539, RL1 AA017540, RC1 DA028279, P20 DA 027844, a Center of Excellence in Gambling Research Award from the National Center for Responsible Gaming, the Research Council of Norway Division for Science, the Department of Psychology at the University of Oslo in Norway, the VA National Center for Posttraumatic Stress Disorder at the West Haven VA Connecticut Clinical Neuroscience Division, and the Veterans Integrated Service Network 1 Mental Illness Research, Education, and Clinical Center (MIRECC). The authors alone are responsible for the writing and the content of this manuscript.

Statement of Interest

The authors report that they have no financial conflicts of interest with respect to the content of this manuscript. Dr Potenza has received financial support or compensation for the following: Dr Potenza has consulted for and advised Boehringer Ingelheim; has consulted for and has financial interests in Somaxon; has received research support from the National Institutes of Health, Veteran's Administration, Mohegan Sun Casino, the National Center for Responsible Gaming and its affiliated Institute for Research on Gambling Disorders, and Forest Laboratories, Ortho-McNeil, Oy-Control/Biotie and Glaxo-SmithKline pharmaceuticals; has participated in surveys, mailings or telephone consultations related to drug addiction, impulse control disorders or other health topics; has consulted for law offices and the federal public defender's office in issues related to impulse control disorders; provides clinical care in the Connecticut Department of Mental Health and Addiction Services Problem Gambling Services Program; has performed grant reviews for the National Institutes of Health and other agencies; has given academic lectures in grand rounds, CME events and other clinical or scientific venues; and has generated books or book chapters for publishers of mental health texts.