Methylthiouracil

A thiourea antithyroid agent that inhibits the synthesis of thyroid hormone. It is used in the treatment of hyperthyroidism. (In Vitro) :HUVECs are treated with various concentrations of MTU (0-20 μM) for 6 h after the addition of LPS (100 ng/mL) for 4 h. MTU inhibits LPS-mediated hyperpermeability in endothelial cells, with the optimal effect occurring at a concentration above 5 μM. The effects of MTU are examined on HUVEC actin cytoskeletal arrangement by immunofluorescence staining of HUVEC monolayers with F-actin labeled fluorescein phalloidin. Control HUVECs exhibit a random distribution of F-actin throughout the cells, with some localization of actin filament bundles at the cell boundaries. Barrier disruption by LPS (100 ng/mL) is manifested by the formation of paracellular gaps in HUVECs. In addition, post-treatment with MTU (10 or 20 μM) results in inhibited formation of LPS-induced paracellular gaps with the formation of dense F-actin rings. To test the cytotoxicity of MTU, cellular viability assays are performed in HUVECs treated with MTU for 24 h. At concentrations up to 20 μM, MTU does not affect cell viability.