7033
Animals were sacrificed at 8h post - dose , and then the distal femoral articular cartilage was subjected to a histological examination and an investigation for gene expression of tumor necrosis factor receptor superfamily , member 12a ( Tnfrsf12a ) ; prostaglandin - endoperoxide synthase 2 ( Ptgs2 ) ; plasminogen activator , urokinase receptor ( Plaur ) ; and matrix metalloproteinase 3 ( Mmp3 ) by qRT - PCR analysis .
 Chemical: prostaglandin
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: prostaglandin