DIFFERETIAL EXPRESSIONS OF COLLAGEN TYPE I AND III IN THE PROXIMAL URETHRA OF DIABETIC RAT WITH AGING

초록

Study design, materials and methods A total of 17 male Sprague-Dawley rats weighing 200 to 500 g. were divided into 2 groups, including 8 into the control and 9 in the experimental group. Diabetes was induced in the two day-old neonates by intraperitoneal administration of streptozotocin (100 mg/kg), which was the Non-insulin dependent diabetes mellitus model. Rats detected as high serum glucose level greater than 200 mg./dl. 12 weeks after injection were considered diabetic. The proximal urethra was obtained under anesthesia at 12, 24 and 36 weeks. Expression levels of collagen type I and III in distal part of proximal urethra were determined by RT-PCR and Western blot analyses, and their distribution was detected by Masson's trichrome staining. Results 1. In Masson's trichrome staining, the distal part of proximal urethra in diabetic rats showed more fibrosis than that in control rats in all three periods. 2. In RT-PCR for mRNA, expressions of collagen Type I mRNA in diabetic rats increased significantly than those in control rats at 12 and 24 week of age. However expressions of collagen Type III mRNA showed no difference between diabetic and control rats. Expressions of collagen Type I mRNA showed 2.5 times more than those of collagen Type III at all 12, 24 and 36 week of age (Fig. 1). 3. In Western blot for collagen, expressions of collagen Type I in diabetic rats showed significantly increased activities than those in control rats at only 12 week of age. Expressions of collagen Type III showed no significant difference between diabetic and control rats. Interpretation of results Collagen expression levels around the proximal urethra in diabetic rats increased more than those in control rats, especially in collagen type I. Concluding message Our findings suggest that these alterations of collagen expression levels in the proximal urethra may be partly responsible for the increased urethral resistance in diabetic rats.