Effects of different carbohydrate diets on cardiac and brain uptake of ¹⁸F-FDG in Wistar rats

Objective: To assess the effects of different carbohydrate diets on cardiac and brain uptake of ¹⁸F-FDG in Wistar rats. Methods: After fed with the standard diet and total energy was kept unchanged, 15 Wistar rats were randomly divided into 3 groups (each n=5); low carbohydrate (LC), intermediate carbohydrate (IC) and high carbohydrate (HC). Each group was fed with every diet for 4 weeks and then underwent MicroPET imaging using ¹⁸F-FDG, respectively. Blood samples from tail vein were collected for the analysis of ketone body, glucose, insulin and glucagon on the next day. SUV_max of heart and brain was obtained with computer processing. Results: SUV _max of heart was 3.27±0.43 in LC group, 10.92±0.89 in IC, and 10.95±0.81 in HC group; SUV_max of brain was 4.78±0.19 in LC group, 4.04±0.15 in IC group and 3.77±0.24 in HC group. There was difference between LC and the other two groups (P<0.01), whereas no difference was found between IC and HC group. Serum ketone body concentration was (726.10±65.95) μmol/L in LC group, which was 6-7 times higher than that in IC and HC group. Serum ketone body was negatively correlated with cardiac SUV_max (r=-0.764, P<0.001), while positively correlated with the brain SUV_max. No difference of serum glucose, insulin and glucagon was found between two groups. Conclusion: Long-term very low carbohydrate diet makes cardiac uptake of FDG decreased and brain uptake increased.