Frokjaer, Vibe Gedsoe2; Erritzoe, David2; Holst, Klaus Kähler2; Jensen, Peter Steen2; Rasmussen, Peter Mondrup1; Fisher, Patrick MacDonald2; Baaré, William2; Madsen, Kathrine Skak2; Madsen, Jacob3; Svarer, Claus2; Knudsen, Gitte Moos2
1 Department of Applied Mathematics and Computer Science, Technical University of Denmark2 Center for Integrated Molecular Brain Imaging3 Copenhagen University Hospital
Stress sensitivity and serotonergic neurotransmission interact, e.g. individuals carrying the low-expressing variants (S and LG) of the 5-HTTLPR promoter polymorphism of the serotonin transporter (SERT) gene are at higher risk for developing mood disorders when exposed to severe stress and display higher cortisol responses when exposed to psychosocial stressors relative to high expressing 5-HTTLPR variants. However, it is not clear how the relation between SERT and cortisol output is reflected in the adult brain. We investigated the relation between cortisol response to awakening (CAR) and SERT binding in brain regions considered relevant to modify the cortisol awakening response. Methods: thirty-two healthy volunteers underwent in vivo SERT imaging with [11C]DASB-Positron Emission Tomography (PET), genotyping, and performed home-sampling of saliva to assess CAR. Results: CAR, defined as the area under curve with respect to increase from baseline, was positively coupled to prefrontal SERT binding (p=0.02), independent of adjustment for 5-HTTLPR genotype. Although S- and LG-allele carriers tended to show a larger CAR (p=0.07) than LA homozygous, 5-HTTLPR genotype did not modify the coupling between CAR and prefrontal SERT binding as tested by an interaction analysis (genotype×CAR). Conclusion: prefrontal SERT binding is positively associated with cortisol response to awakening. We speculate that in mentally healthy individuals prefrontal serotonergic neurotransmission may exert an inhibitory control on the cortisol awakening response.
European Neuropsychopharmacology, 2013, Vol 23, Issue 4, p. 285-294