Interindividual variability and lateralization of μ-opioid receptors in the human brain
Tatu Kantonen,
Tomi Karjalainen,
Janne Isojärvi,
Pirjo Nuutila,
Jouni Tuisku,
Juha Rinne,
Jarmo Hietala,
Valtteri Kaasinen,
Kari Kalliokoski,
Harry Scheinin,
Jussi Hirvonen,
Aki Vehtari,
Lauri Nummenmaa
Affiliations
Tatu Kantonen
Turku PET Centre, University of Turku, Finland; Clinical Neurosciences, University of Turku and Turku University Hospital, Finland; Corresponding author. Turku PET Centre c/o Turku University Hospital, P.O. Box 52, FI-20521, Turku, Finland.
Tomi Karjalainen
Turku PET Centre, University of Turku, Finland; Turku PET Centre, Turku University Hospital, Finland
Janne Isojärvi
Turku PET Centre, University of Turku, Finland
Pirjo Nuutila
Turku PET Centre, University of Turku, Finland; Department of Endocrinology, Turku University Hospital, Finland
Jouni Tuisku
Turku PET Centre, University of Turku, Finland
Juha Rinne
Turku PET Centre, University of Turku, Finland; Clinical Neurosciences, University of Turku and Turku University Hospital, Finland
Jarmo Hietala
Turku PET Centre, University of Turku, Finland; Department of Psychiatry, University of Turku and Turku University Hospital, Finland
Valtteri Kaasinen
Turku PET Centre, University of Turku, Finland; Clinical Neurosciences, University of Turku and Turku University Hospital, Finland
Kari Kalliokoski
Turku PET Centre, University of Turku, Finland
Harry Scheinin
Turku PET Centre, University of Turku, Finland
Jussi Hirvonen
Turku PET Centre, University of Turku, Finland
Aki Vehtari
Helsinki Institute for Information Technology HIIT, Department of Computer Science, Aalto University, Finland
Lauri Nummenmaa
Turku PET Centre, University of Turku, Finland; Department of Psychology, University of Turku, Finland
Alterations in the brain’s μ-opioid receptor (MOR) system have been associated with several neuropsychiatric disorders. Central MOR availability also varies considerably in healthy individuals. Multiple epidemiological factors have been proposed to influence the MOR system, but due to small sample sizes the magnitude of their influence remains inconclusive. We compiled [11C]carfentanil positron emission tomography scans from 204 individuals with no neurologic or psychiatric disorders, and estimated the effects of sex, age, body mass index (BMI) and smoking on [11C]carfentanil binding potential using between-subject regression analysis. We also examined hemispheric differences in MOR availability. Older age was associated with increase in MOR availability in frontotemporal areas but decrease in amygdala, thalamus, and nucleus accumbens. The age-dependent increase was stronger in males. MOR availability was globally lowered in smokers but independent of BMI. Finally, MOR availability was higher in the right versus the left hemisphere. The presently observed variation in MOR availability may explain why some individuals are prone to develop MOR-linked pathological states, such as chronic pain or psychiatric disorders. Lateralized MOR system may reflect hemispheric work specialization in central emotion and pain processes.
