title: Age-related diurnal effect on D2 receptor binding: a preliminary PET study.
abstract: Animal research has shown a diurnal variation in dopamine neurotransmission, with a reduced release at night. Variations in biomarkers for the dopamine system over the day have, however, not been investigated in human subjects. In this preliminary PET study, we used the radioligands [11C]raclopride and [11C]FLB 457 to determine dopamine D2-receptor binding in 16 human subjects in the morning and evening on the same day. The average difference between morning and evening examinations did not indicate a diurnal effect on D2 receptor availability. However, when age was taken into account in the analysis, a pattern emerged where individuals in the lower age range showed reduced evening binding while in older subjects binding potential increased. The product-moment correlation between morning-evening change and age was statistically significant in insula, medial frontal cortex and rostral anterior cingulate. The findings, if replicated, have direct relevance for applied PET studies and could also prove relevant with regard to age effects on dopamine-related behaviour such as arousal and cognitive performance.
authors.affiliation: Karolinska Institutet, Department of Clinical Neuroscience, Psychiatry Section, Stockholm, Sweden. simon.cervenka@ki.se
authors.forename: Simon
authors.initials: S
authors.lastname: Cervenka
authors.forename: Christer
authors.initials: C
authors.lastname: Halldin
authors.forename: Lars
authors.initials: L
authors.lastname: Farde
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D000704:Analysis of Variance; D001921:Brain / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D001931:Brain Mapping; D002250:Carbon Radioisotopes / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011485:Protein Binding; D011759:Pyrrolidines / Q000378:metabolism; D020891:Raclopride / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D012457:Salicylamides / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2; D012457:Salicylamides; C065065:FLB 457; D020891:Raclopride