An Immunohistochemical Study of Matrix Metalloproteinase 2 and 9 in the Left Ventricle of the Heart of Preterm Born Rats in the Late Period of Ontogenesis

Immunohistochemical detection of matrix metalloproteinase (MMP) 2 and 9 was carried out in the myocardium of the left ventricle of preterm born (21 and 21.5 days of pregnancy) and full-term (22 days of pregnancy) rats on days 42, 56, and 180 of the postnatal period of ontogenesis. The intensity of immunopositive staining was assessed semiquantitatively. Preterm birth leads to increased immunopositive reaction intensity to MMP-2 and MMP-9 in the wall of the left ventricle of the rat heart. An increase in the intensity of the positive reaction to MMP-2 in the left ventricle of the heart of rats is observed the earlier, the greater the degree of prematurity. The intensity of the positive reaction to MMP-9 in the left ventricle of the heart of male rats increases with increasing degree of prematurity. An increase in the intensity of the positive reaction to MMP-2 and MMP-9 in the wall of the left ventricle of female rats due to preterm birth is determined exclusively in animals born on the 21st day of pregnancy, that is, with a greater degree of prematurity.