The International Journal of Neuropsychopharmacology

Brief Report

Sex differences in striatal dopamine D2/D3 receptor availability in smokers and non-smokers

Amira K. Browna1a2, Mark A. Mandelkerna2a3, Judah Farahia2, Chelsea Robertsona4, Dara G. Ghahremania1, Brittany Sumerela1, Nathasha Moallema1 and Edythe D. Londona1a4a5 c1

a1 Department of Psychiatry and Biobehavioral Sciences, UCLA, Los Angeles, CA, USA

a2 Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA, USA

a3 Department of Physics, UC Irvine, Irvine, CA, USA

a4 Department of Molecular and Medical Pharmacology, UCLA, Los Angeles, CA, USA

a5 Brain Research Institute, UCLA, Los Angeles, CA, USA

Abstract

In previous research, nicotine-dependent men exhibited lower putamen D2/D3 dopamine-receptor availability than non-smokers (Fehr et al. 2008), but parallel assessments were not performed in women. Women and men (19 light smokers, 18 non-smokers) were tested for differences due to sex and smoking in striatal D2/D3 dopamine-receptor availability, using positron emission tomography with [18F]fallypride. Receptor availability was determined using a reference region method, in striatal volumes and in whole-brain, voxel-wise analysis. Significant sex×smoking interactions were observed in the caudate nuclei and putamen. Post-hoc t tests showed that male smokers had significantly lower D2/D3 dopamine-receptor availability than female smokers (−17% caudate, −21% putamen) and male non-smokers (−15% caudate, −16% putamen). Female smokers did not differ from non-smokers. Whole-brain analysis demonstrated no statistically significant voxels or clusters. These results suggest that low receptor availability may confer vulnerability to nicotine dependence or that smoking selectively affects D2/D3 receptor down-regulation in men but not women.

(Received June 07 2011)

(Reviewed July 28 2011)

(Revised November 18 2011)

(Accepted December 12 2011)

(Online publication January 16 2012)

Correspondence:

c1 Address for correspondence: E. D. London, Ph.D., UCLA Semel Institute of Neuroscience and Biobehavioral Sciences, 760 Westwood Plaza, Rm. C8-831, Los Angeles, CA 90045, USA. Tel.: (310)825-0606 Fax: 310-825-0812 Email: elondon@mednet.ucla.edu