Are the Matrix Metalloproteinases 2 and 9 beeing expressed in the mucosa of the rat small intestine during its intrauterine and postnatal life development?

MMP-2 and MMP-9 are proteins with well stablished roles on the remodeling of tissue during morphogenesis. This study aimed to evaluate the activity and expression of the MMP-2 and MMP-9 in the rat small intestine mucosa layer on 15th and 18th days of intratuterine life (i.u.) and at 3rd, 10th, 17th, 25th, and 32th days after birth (a.b.). Samples were submitted to zimography, immunohistochemistry methods and Masson trichrome staining. Results showed that MMP-2 and MMP-9 were not expressed in the small intestine epithelium during intrauterine life. MMP-9 was immunolocalized in the villi goblet cells and in the lamina propria in cells identified as being the mast cells (a.b.). We concluded that in the i.u. and a.b. life the MMP-2 and MMP-9 were not expressed in the small intestine epithelium. However, after birth, because MMP-9 was expressed in the mast cels present in the lamina propria it may be involved in the remodeling process of the innate immunity that occurs during the small intestine development.