Glucocorticoid effects on vascular connective tissue during repair. Importance of dose level and pre- and post-injury treatment. Morphological and biochemical studies.

Abstract

ABSTRACT Aorta of male albino rabbits were subjected to a single mechanical dilatation injury and the effects of different daily doses of prednisolone on the metabolism of collagen and glycosaminoglycans as well as on the content of alpha-amino nitrogen, RNA, DNA, water and fat and the histology of the descending thoracic aorta were analyzed 10 days after the injury. The effects of pre- and post-injury treatment with prednisolone were compared. Prednisolone inhibited the intimal thickening. This effect was enhanced by pre-injury treatment. Prednisolone also inhibited the biosynthesis of non-dialysable [14C]hydroxyproline-collagen, but increased the relative degradation of collagen in a dose dependent manner. The biosynthesis of glycosaminoglycans was decreased while prednisolone had no effect on the concentration and total amount of glycosaminoglycans, collagen, protein, RNA, DNA and fat. Finally the aortic content of water was decreased during treatment with prednisolone also in a dose dependent manner. It is concluded that the action of prednisolone on vascular collagen and water during repair is dose dependent and that the inhibitory action of prednisolone on the intimal thickening is enhanced by pre-injury treatment.