Early molecular changes associated with streptozotocin-induced diabetic bladder hypertrophy in the rat

We describe early alterations in rat bladder gene expression which may relate to the development of diabetic bladder dysfunction in a streptozotocin model of inducible diabetes. Utilizing cDNA probes, the gene products sulfated glycoprotein-2 (SGP-2), transforming growth factor-beta (TGF-beta), beta-actin (beta-actin), N-ras and beta nerve growth factor (beta-NGF), were quantitated in bladders of male Sprague-Dawley rats at 1, 2, 4 and 6 weeks after induction of diabetes with streptozotocin (STZ). beta-actin and SGP-2 expression were transiently increased at 1 and 4 weeks after induction, respectively. TGF-beta was not altered over the period of the study. N-ras was reduced at all times compared with control rat bladders. Transcripts encoding beta-NGF were dramatically increased in STZ-treated rats at 4 weeks. None of these changes were seen in diuresis control group fed 5% sucrose. Our results suggest that during the early stages of diabetes, cellular hypertrophy, growth and remodeling are occurring concomitantly with cellular injury and programmed cell death. Furthermore, the transient increase in expression of beta-NGF mRNA may represent a compensatory response to the diabetic condition in an attempt to attract further innervation and revascularization.