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ABSTRACT: 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has become a useful imaging tool for inflammatory diseases. In this study we investigated the effects of rolipram, a selective phosphodiesterase type 4 inhibitor, on 14C-deoxyglucose (DG) uptake in inflammatory lesions and other normal tissues, and attempted to improve the inflammation/muscle ratio.
To induce inflammation, mice were inoculated with turpentine oil. Inflammation-bearing mice were pretreated with rolipram (3 mg/kg i.p. or i.v.), and the effect on 14C-DG uptake was measured using a tissue dissection method and autoradiography. The inflammatory tissue samples were stained with haematoxylin and eosin.
Rolipram (3 mg/kg i.p.) significantly decreased 14C-DG uptake in normal tissues like brain, heart and skeletal muscle (brain 31%, heart 60%, skeletal muscle 61%). On the other hand, 14C-DG uptake in inflammatory lesions was not significantly altered by pretreatment with rolipram. The inflammation/muscle ratio of 14C-DG uptake (30 min after tracer injection) was enhanced from 1.1 to 2.8 by rolipram. An autoradiographic study revealed heterogeneous distributions of 14C-DG in the inflammatory lesions and skeletal muscle of animals that were not treated with rolipram. Pretreatment with rolipram significantly attenuated the intramuscular distribution of 14C-DG, producing a relatively homogeneous distribution of radioactivity.
These results indicate that rolipram decreased 14C-DG uptake in skeletal muscle by activation of the adenosine 3',5'-cyclic monophosphate system, whereas 14C-DG uptake in inflammatory lesions was not significantly altered. Therefore, rolipram may be a valuable tool for improving the visualisation of inflammatory lesions in clinical PET studies employing FDG.
European journal of nuclear medicine and molecular imaging 03/2005; 32(2):163-6. DOI:10.1007/s00259-004-1616-8 · 5.22 Impact Factor