Expression of epidermal growth factor, basic fibroblast growth factor and insulin growth factor-1 and relation to myocyte regeneration of obstructed ureters in rats

Abstract

To investigate the roles of epidermal growth factor (EGF), basic fibroblast growth factor (bFGF) and insulin growth factor-1 (IGF-1) in the myocyte regeneration of obstructed ureters. The expression of EGF, bFGF, IGF-1 and proliferation cell nuclear antigen (PCNA) was studied immunohistochemically in 54 female Sprague-Dawley rats. Tissue damage to the smooth muscle layer in the obstructed ureters was aggravated during the period of obstruction. The expression of EGF, bFGF and IGF-1 in myocytes was detected using the method of concurrent immunohistochemical staining. The expression of EGF, bFGF and IGF-1 in the smooth muscle layer was found from Day 14 after ligation. The expression of EGF, bFGF and IGF-1 increased to a peak on Day 21 and then declined. The expression of PCNA in the smooth muscle layer was also found from Day 14 after ligation and increased to a peak on Day 21. The expressions of EGF, bFGF and IGF-1 were significantly correlated with the expression of PCNA in the smooth muscle layer (r=0.7982, 0.6264 and 0.5840, respectively; p-values all <0.002). Co-expression of EGF, bFGF, IGF-1 and PCNA was determined using the method of double immunofluorescence staining. Co-expression of PCNA was observed in 34% of EGF-positive myocytes, 53.6% of bFGF-positive myocytes and 41.1% of IGF-1-positive myocytes at Day 21 post-ligation. Expression of EGF, bFGF and IGF-1 may contribute to myocyte regeneration of damaged ureters in rats with obstructive uropathy.