Abstract
Diabetes mellitus increases oxidative stress due to hyperglycemia, resulting in the degeneration of rotator cuff tissue. Currently, there is no established method to non-invasively assess the extent of this oxidative stress. To address this, we aimed to investigate the relationship between the accumulation of advanced glycation end-products (AGEs), a marker of oxidative stress, and transcutaneous autofluorescence intensity in rotator cuff tissue harvested from diabetic rats. Ten control Sprague-Dawley (SD) rats and streptozotocin-induced diabetic rats (n = 10 per group) were used. The rats were euthanized eight and 16 weeks after the induction of diabetes, and rotator cuff attachment sites were collected and histologically analyzed. Prior to euthanasia, autofluorescence intensity was measured transcutaneously in the rotator cuff area. The expressions of AGEs and type I collagen were evaluated immunohistochemically with specific antibodies and the stained areas were quantified. All data were statistically analyzed using the Mann-Whitney U test. Correlation analysis was performed for skin autofluorescence intensity and the percentage of AGEs staining area using Spearman's rank correlation coefficient. The immunohistochemical expression of AGEs at the rotator cuff attachment sites and transcutaneous AGEs measurements were significantly higher in diabetic rats than in the control group at 16 weeks. There was no significant difference in the level of type 1 collagen between the two groups. This study reveals that the accumulation of AGEs in rotator cuff tissue increases due to prolonged hyperglycemia in diabetes. In addition, transcutaneous skin fluorescence intensity may be related to histological oxidative stress at the rotator cuff.