Decorin, a small dermatan sulphate
proteoglycan, has been postulated to interact with other components of the extracellular matrix. We examined time-dependent changes of
decorin in the
infarct zone after experimentally induced
myocardial infarction in rats by Northern blotting, in situ hybridization, and immunohistochemistry. The expression of
decorin mRNA was compared to that of
biglycan mRNA. Northern blotting demonstrated that the
decorin mRNA expression was not increased in the
infarct zone on day 2, while increased
biglycan mRNA was observed at that time (average 3.1-fold increase).
Decorin mRNA expression was increased on day 7, and reached a peak (average 2.2-fold increase) around day 14.
Biglycan mRNA expression also reached a peak level around day 14 (average 13.3-fold increase). In situ hybridization revealed that
mRNA signals for
decorin did not appear in the
infarct zone on day 2, while
biglycan mRNA signals were observed.
Decorin mRNA signals were observed in spindle-shaped mesenchymal cells in the
infarct peripheral zone on day 7. The
decorin mRNA signals appeared later than those of
biglycan. Immunopositive staining for
decorin was observed in the
infarct zone on day 7. The present results demonstrated a time-dependent increase in
decorin mRNA expression in mesenchymal cells in the
infarct zone in rats.
Decorin mRNA appeared later and was increased to a lower extent in the
infarct zone than
biglycan mRNA.