Abstract: To improve the brain uptake of the benzamide compound 125I-AIBZM (S)- 5-125I -N-(1-ethyl-2-pyrrolidinyl) methyl-4-amine -2-methoxy- benzamide, the structure modification was performed resulting in a new compound 125I-DMAIBZM ((S)-5-125I-Iodo-N-(1-ethyl-2-pyrrolidinyl)methyl-4-dimethyl- amine-2-methoxy-benzamide) produced. Labeling was achieved by Iodogen method, with 74% radiochemical yield. After HPLC purification, radiochemical purity >99% was obtained. The receptor binding affinity of DMABZM to rat brain membrane（IC50为2.9589×10-7 mol?L-1）have shown high affinity to dopamine D2 receptor. The mice biodistribution data for 125I-DMAIBZM (the ratio striatum/cerebellum>6.5) indicates a good distribution in striatum with high specificity and affinity. The lipophilicity of 125I-DMAIBZM is significantly higher than that of 125I-AIBZM. Conclusion: 125I（123I）-DMAIBZM is in a promise state for Dopamine D2 receptor Imaging.

Key words: Dopamine D2 receptor, 125I；receptor imaging