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DOI: 10.1055/s-0039-1683513
Reward sensitivity but not weight loss following gastric bypass surgery in obese individuals is accompanied with changes in central serotonin transmission
Publikationsverlauf
Publikationsdatum:
27. März 2019 (online)
Ziel/Aim:
Roux-en-Y gastric bypass (RYGB) surgery is currently the most effective treatment for morbid obesity, but the specific mechanisms underlying its weight lowering effects remain elusive. One current assumption is that changes in brain reward processing through the central monoaminergic system substantially contributes to the outcome of RYGB on body weight. We investigated whether there is a change in reward sensitivity in patients with severe obesity (BMI> 40 kg/m2) before and 6 months after RYBG surgery and whether this relates to changes in central serotonin transporter (SERT) availability and BMI.
Methodik/Methods:
SERT availability was quantified using PET (ECAT EXACT HR+) and SERT-selective [11C]DASB (465 ± 69 MBq) in twelve individuals (BMI 45 ± 4 kg/m2, 6 female, 44 ± 12 years) before and 6 months after RYGB surgery. As the PET outcome measure, regional binding potential BPND was calculated by applying a multi-linear reference tissue model after individual PET-MR coregistration. To assess reward sensitivity, the behavioural activation system reward scale (BAS-Reward) was applied at baseline and at follow-up investigations, while symptoms of depression were rated by using Beck Depression Inventory (BDI).
Ergebnisse/Results:
Mean change in BMI and weight loss in RYGB patients over 6 months were 10 ± 3 kg/m2 and 32 ± 9 kg, respectively, while BAS-Reward changed from 11.5 ± 4.9 to 14.1 ± 4.1 (p = 0.4). BPND before and after RYGB surgery did not differ in brain reward regions (e.g., in the ventral striatum 1.57 ± 0.46 and 1.78 ± 0.34, p = 0.3). However, ΔBAS-Reward and ΔSERT-BPND were significantely associated in the OFC (r =-0.94, p < 0.01) and the ventral striatum (r =-0.74, p = 0.05). Neither ΔBMI nor ΔBDI correlated with ΔBAS-Reward/ΔBPND.
Schlussfolgerungen/Conclusions:
Although patients undergoing RYGB surgery experienced significant weight loss, there was no direct association with reward sensitivity or brain SERT availability. Thus, other factors may have a stronger impact on the weight lowering efficacy of this intervention in obese individuals. Nonetheless, the data further support SERT availability as a biological factor of reward sensitivity.
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