Targeting islet cell using 18F-Fallypride: in vitro and histoautoradiography study / 中华核医学与分子影像杂志

ABSTRACT

Objective To evaluate the feasibility of dopamine D2 receptor imaging agent (s)-(-)-N-(1-allylpyrrolidine-2-N-methyl)-5-(3-18F)-2,3-dimethoxy Benzamide (18F-Fallypride) for targeting islet cell imaging.Methods (1) Cytology experimentIslet cells of 15×103 cells/well were incubated with 3.70 kBq/well 18F-Fallypride for 1 h and the uptake rate of cells was calculated (cell counts/(supernatant counts + cell counts)× 100％).Under the same experiment conditions,6 inhibiting groups were administrated with different concentration of dopamine inhibitors droperidol (1.0× 10-6,4.0× 10-6,2.0× 10-5,1.0× 10-4,5.0× 10-4 and 1.0× 10-3 mol/L,respectively).After 30 min,3.70 kBq of 18F-Fallypride was added to each inhibiting group,and the inhibiting rate was calculated.(2) Autoradiography18 normal ICR mice were divided into 6 groups.For group A,ICR mice were injected with 18F-Fallypride (55 ± 5) MBq/mice through tail vein.For the other 5 inhibiting groups (group B-F),ICR mice were injected with different doses of droperidol (0.2,0.4,0.6,0.8 and 1.0 mg/kg,respectively),and after 30 min 18F-Fallypride were injected through tail vein.Ten minutes later,pancreas of ICR mice was taken for preparation of tissue section autoradiography.The data were analyzed by one-way analysis of variance and the least significant difference t test.Results (1) The 18F-Fallypride uptake rate of control group was (18.40± 1.21) ％.The uptake rates of inhibiting groups were (16.11±1.37)％,(15.76±0.99)％,(13.90±1.02)％,(8.86±0.73)％,(7.26±0.62)％ and (6.92±0.58)％,respectively,which decreased with the decreasing concentration of droperidol (F=50.01,P＜0.01).When the concentration of droperidol was 1.0× 10-4 mol/L,the uptake rate reached the lowest with inhibiting rate of 51.85％.(2) The autoradiography showed that the pancreas gray scale value of group A was 1.21×106 digital light units (DLU)/mm2.The pancreas gray scale value of groups B to F decreased with increasing concentration of inhibitor0.93× 106,0.77× 106,0.59× 106,0.32× 106 and 0.25×106 DLU/mm2,respectively.Conclusions 18F-Fallypride may specifically and efficiently bind to dopamine receptors of islet cells.It may be a potential tracer for islet cells imaging.