Endocrine Abstracts

Eating behavior is determined by both homeostatic and hedonic values. We investigated the association of hedonic value with striatal dopamine transporter (DAT) availability sub-regionally. An intravenous bolus injection of ¹⁸F-FP-CIT was administered after the infusion of glucose or placebo, and the emission data were acquired over 90 mins. DAT availability, binding potential (BP_ND), were measured via the simplified reference tissue method. Subjects were assessed with sensory taste test of sucrose solutions. The ’most liked’ sucrose concentration (%) was determined as the hedonic rating for sucrose. Twenty healthy males with the mean age of 23.9 ± 1.7 years (range 22 ~ 28 years) were participated in this study. The 12% sucrose solution received the highest liking score. BMI was associated neither with the ’most liked’ sucrose concentration (r = –0.1812; P = 0.4446). After glucose loading, BPNDs of putamen were significantly increased (P = 0.0195, mean percentage change of BP_ND ± standard deviation; + 33.7 ± 51.7%), and those of caudate nucleus showed the increasing trend (P = 0.0601, + 70.4 ± 113.6%), while those of ventral striatum were not significantly different (P = 0.3330, + 29.6 ± 94.0%) compared with those after placebo loading (Figure 1). The relationships between the ’most liked’ sucrose concentration (%) and BPNDs were investigated both by VOI-based and voxel-based analysis. With a VOI-based analysis, after glucose loading, the ’most liked’ sucrose concentration (%) was negatively associated with BPNDs of caudate nucleus (r = –0.5437, P = 0.0132) and showed the trend of positive association with those from ventral striatum (r = 0.4115, P = 0.0715). Slopes of regression lines were significantly different according to sub-regions of striatum (F = 6.150, P = 0.0039) (Figure 2A). After placebo loading, the ’most liked’ sucrose concentration (%) was not associated with BPNDs of ventral striatum (r = –0.1285, P = 0.5893), caudate nucleus (r = –0.2331, P = 0.3227) and putamen (r = –0.2506, P = 0.2866) without the significant difference in slopes of regression lines (F = 0.1235, P = 0.8841) (Figure 2B). With a voxel-based analysis, the ’most liked’ sucrose concentration (%) was not associated with DAT availabilities of brain regions except for left putamen (MNI coordinates; –24 12 8, k = 87, T = 3.51) and left caudate nucleus (MNI coordinates; –18 14 12; –16 –6 24, k = 104, T = 3.36; 3.07) negatively after glucose loading (Figure 3). In conclusion, we have highlighted that striatal DAT increased after glucose loading in dorsal striatum, not in ventral striatum. These changes of striatal DAT were sub-regionally associated with the hedonic rating of sucrose from each subject.