The profile of the extracellular matrix changes in the aorta after sympathectomy in the hypercholesterolemic rats

We previously showed that sympathectomy induces thickened intima and decreases the expression of cytoskeletal proteins associated with a differentiated smooth muscle cell (SMC) phenotype in hypercholesterolemic rats. In the present study, we sought to determine the effect of sympathectomy on various components of the extracellular matrix (ECM) in the aorta from these animals, since the state of SMC differentiation depends on the nature of ECM components. Collagen types I and III, previously reported to be associated with SMC dedifferentiation, and collagen VI, elastin, laminin and elastin-laminin receptor (E/L-R), previously reported to be associated with SMC differentiation, were analyzed by western immunoblot and confocal microscopy in abdominal aortae from sham rats and hypercholesterolemic rats sympathectomized with guanethidine. Both western immunoblot and immunohistological analysis showed an increase in collagens I and III (more for collagen I), with abundant labeling in the media, adventitia and thickened intima in sympathectomized aortae. Collagen IV labeling was decreased in the media and adventitia and was weak in the thickened intima in sympathectomised aortae. The E/L-R increased and was abundantly labeled in the media and weakly in the thickened intima in sympathectomized aortae. Elastin and laminin decreased and appeared less labeled in the media in the sympathectomised aortae. In the thickened intima, laminin was slightly labeled while elastin was not obviously labeled. These data show that sympathectomy favors the ECM features reported in association with a dedifferentiated/immature SMC phenotype and intimal thickening, probably by actions on both SMCs and fibroblasts.