Effects of low-dose insulin or a soluble guanylate cyclase activator on lower urinary tract dysfunction in streptozotocin-induced diabetic rats

To examine the effects of low-dose insulin or a soluble guanylate cyclase activator (sGC) on lower urinary tract dysfunction (LUTD) in rats with diabetes mellitus (DM).Female Sprague-Dawley rats were divided into non-DM control (N), DM induced by streptozotocin (65 mg/kg), with low-dose insulin (DI), DM with vehicle (D), and DM with sGC (GC) groups. In GC group, BAY 60-2770 (1 mg/kg/day) was orally administered in 6-8 weeks after DM. Voiding assay at 2, 4, and 8 weeks after DM, cystometry, and urethral pressure recordings at 8 weeks of DM were performed. mRNA levels of NO-related markers and cGMP protein levels in the urethra, and ischemia and inflammation markers in the bladder were evaluated by RT-PCR.Moderate levels of high blood glucose were maintained in Group DI versus Group D. The 24-h voided volume was significantly higher in Group D versus Groups N and DI. Non-voiding contractions were significantly greater, and voiding efficiency and urethral pressure reduction were significantly lower in Group D versus Groups N, DI, and GC. Urethral cGMP levels were significantly lower in Group D versus Groups N and GC. mRNA levels of PDE5 in the urethra and ischemia and inflammation markers in the bladder increased in Group D versus Group N or DI was reduced after sGC treatment.DI rats with a lesser degree of bladder and urethral dysfunction might be useful as a slow-progressive DM model. sGC activation could be an effective treatment of LUTD in DM.