Changes in the biomechanical properties of skin and aorta induced by corticotrophin treatment.

The work presented here is an investigation of the effect of elevated levels of corticosteroids on the biophysical properties of skin, aorta and muscle tendon. Rats were given corticotrophin injections for 10, 30 and 60 days to elevate the level of plasma endogenous corticosteroids. The corticotrophin treatments did not change the water or collagen content of specimens from dorsal skin, thoracic aorta and peroneal muscle tendons, tested mechanically. Changes became evident after longer treatment times. For both skin and aorta, the tensile strength, elastic stiffness and failure energy were increased after 60 days of treatment. The corticotrophin treatment did not influence the mechanical properties of muscle tendons. Complete reversibility of changes in the mechanical properties induced by 30 days of corticotrophin treatment was found after an additional period of 30 days of saline injections. This study indicates that an increased level of plasma corticosteroids elicited by corticotrophin treatment may increase the stiffness of the connective tissue of the organism. In the aorta this results in loss of capacitive function with increased haemodynamic strain on the aortic wall.