Use of [<sup>18</sup>F]FDG/PET to access the rosmarinic acid anti-inflammatory effect in a mouse sponge implant model

Positron emission tomography (PET) is one of the most sensitive and effective imaging techniques for detecting very low concentrations of specific radiotracers. It is suitable for analyzing biochemical, metabolic, physiological and functional information at the molecular level in vivo and non-invasively. PET using 2-deoxy-2[18F]-fluoro-D-glucose ([18F]FDG) can be used to identify sites of inflammation and other pathologies and to monitor the efficacy of treatment. This technique can be used to study the effect of rosmarinic acid (RA) in various preclinical models. RA is a natural compound with promising antioxidant and anti-inflammatory effects. Therefore, the aim of this study is to investigate the anti-inflammatory potential of RA and the efficacy of PET/[18F]FDG in localizing inflammation and assessing response to treatment. A sponge implant model in mice was used for this purpose. All experiments were performed with male BALB/c mice aged 6 to 9 weeks and weighing 18 to 22 g, with 5 animals per group (10 animals in total throughout the study). Methods: The mice were implanted with sponge-like polyurethane discs to induce local inflammation. The animals were divided into two experimental groups: those treated with a vehicle and those treated with RA. PET scans with [18F]FDG were performed to evaluate the inflammatory process. Results: The results obtained with [18F]FDG showed a decrease in inflammatory cell infiltrates in the sponge after treatment with RA. Conclusion: The use of [18F]FDG demonstrated its efficacy in quantitatively evaluating the inflammatory process in the mouse subcutaneous sponge model as well as the anti-inflammatory effect of RA.