Biodistribution of andrographolide to assess the interior‐exterior relationship between the lung and intestine using microPET

BACKGROUND: One classic traditional Chinese medicine theory is that the “lung and intestine are exterior‐interiorly related”; however, this has not been confirmed experimentally. The aim of this study was to provide a biological basis for the theory by measuring the tissue distribution of andrographolide. METHODS: Acute pneumonia was induced in a mouse model by repeated stimulation with lipopolysaccharide. The distribution of andrographolide in mice was observed by positron emission tomography (PET) imaging with [(18)F]‐labeled andrographolide, and changes in the in vivo distribution before and after modeling were compared. Subsequently, the consistency of pathological changes in lung and intestine was confirmed by observation of pathological sections. Finally, the results were verified by cytokine detection. RESULTS: The value of organ uptake, pathological changes and inflammatory factor expression of the lung and intestine were consistent. The concentration of andrographolide in the lung and intestine increased significantly, and was confirmed by pathology and enzyme‐linked immunosorbent assays (ELISA). CONCLUSIONS: Micro‐positron emission tomography (microPET) can be used to visually observe the distribution of medicinal ingredients in vivo, and [(18)F]‐andrographolide can be used as a tool to assess the interior‐exterior relationship between the lung and intestine.