Translocator protein (TSPO) expression is closely related with neuroinflammation and neuronal damage which might cause several central nervous system diseases. Herein, a series of TSPO ligands (11a–c and 13a–d) with a 2-phenylpyrazolo[1,5-a]pyrimidin-3-yl acetamide structure were prepared and evaluated via an in vitro binding assay. Most of the novel ligands exhibited a nano-molar affinity for TSPO, which was better than that of DPA-714. Particularly, 11a exhibited a subnano-molar TSPO binding affinity with suitable lipophilicity for in vivo brain studies. After radiolabeling with fluorine-18, [¹⁸F]11a was used for a dynamic positron emission tomography (PET) study in a rat LPS-induced neuroinflammation model; the inflammatory lesion was clearly visualized with a superior target-to-background ratio compared to [¹⁸F]DPA-714. An immunohistochemical examination of the dissected brains confirmed that the uptake location of [¹⁸F]11a in the PET study was consistent with a positively activated microglia region. This study proved that [¹⁸F]11a could be employed as a potential PET tracer for detecting neuroinflammation and could give possibility for diagnosis of other diseases, such as cancers related with TSPO expression.

转运蛋白（TSPO）的表达与神经发炎和神经元损害密切相关，神经炎和神经元损害可能会引起多种中枢神经系统疾病。本文中，制备了一系列具有2-苯基吡唑并[1,5 - a ]嘧啶-3-基乙酰胺结构的TSPO配体（11a – c和13a – d），并通过体外结合试验进行了评估。大多数新型配体对TSPO表现出纳摩尔摩尔亲和力，优于DPA-714。特别地，11a在体内脑研究中表现出亚纳米摩尔TSPO结合亲和力和适当的亲脂性。用氟18放射性标记后，[ ¹⁸ F]11a用于大鼠LPS诱发的神经炎症模型的动态正电子发射断层扫描（PET）研究；与[ ¹⁸ F] DPA-714相比，炎症病变清晰可见，靶标与背景的比率更高。解剖后大脑的免疫组织化学检查证实，PET研究中[ ¹⁸ F] 11a的摄取位置与小胶质细胞阳性激活区域一致。这项研究证明[ ¹⁸ F] 11a可用作检测神经炎症的潜在PET示踪剂，并可能为诊断其他疾病（例如与TSPO表达相关的癌症）提供可能性。