The Effect of Low-Intensity Extracorporeal Shockwave Treatment on the Urinary Bladder in an Experimental Diabetic Rat Model

Abstract

Purpose: Preclinical data increasingly support an impact of low-intensity extracorporeal shockwave therapy (Li-ESWT) on the bladder. We investigated the molecular effects of Li-ESWT on the bladder of a streptozotocin-induced diabetic rat model.

Methods: Fifteen 8-week-old male Wistar rats were randomized into 3 groups: a control group (n=5), a group of diabetic rats without treatment (diabetes mellitus [DM], n=5) and a group of diabetic rats treated with Li-ESWT (DM-ESWT, n=5). A single intraperitoneal dose of streptozotocin (60 mg/kg) was used to induce diabetes. Twenty days after diabetes induction, each rat in the DM-ESWT group received 300 shockwaves with an energy flux density of 0.09 mJ/mm2. Sessions were repeated 3 times/week for 2 weeks, followed by a 2-week washout period. Total RNA from bladder tissue was extracted, cDNA was synthesized, and quantitative real-time polymerase chain reaction was performed to analyze the expression pattern of transient receptor potential vanilloid 1 (Trpv1), interleukin-1β (Il1b), and the muscarinic receptors M1, M2, and M3 (Chrm1, Chrm2, and Chrm3).

Results: The expression of Trpv1, Il1b, and Chrm2 genes was significantly different between the 3 groups (P=0.002, P<0.0001, and P=0.011, respectively; 1-way analysis of variance). In the DM group, the expression of all genes was higher than in the control group, but statistical significance was observed only for Trpv1 and Il1b (P=0.002 and P<0.0001, respectively). Li-ESWT significantly reduced the expression of Il1b and Chrm2 (P=0.001 and P=0.011, respectively), whereas a nonsignificant tendency for reduced expression was noted for Trpv1 (P=0.069).

Conclusion: The induction of diabetes was associated with increased expression of genes related to mechanosensation, inflammation/ischemia, and contraction in the rat bladder. Li-ESWT reduced the expression of IL1b, Chrm2, and to a lesser extent Trpv1 toward the control levels, suggesting the therapeutic potential of this treatment modality for diabetic cystopathy.

Keywords: Diabetes mellitus; Extracorporeal shockwave therapy; Urinary bladder.

Fig. 1.

(A) The application of Li-ESWT in the treatment group on the urinary bladder of an experimental rat. (B) The treatment schedule. Li-ESWT, low-intensity shockwave therapy; EFD, energy flux density; qRT-PCR, quantitative real-time polymerase chain reaction.

Fig. 2.

Histograms of mRNA expression of transient receptor potential vanilloid 1 (Trpv1) (A), interleukin-1β (Il1b) (B), and the muscarinic receptors M1, M2, and M3 (Chrm1, Chrm2, and Chrm3) (C-E) respectively, relative to Gapdh (reference gene), for the 3 experimental animal groups. The y-axis values are the relative quotient as determined by the ΔΔCt method from quantitative real-time polymerase chain reaction. Bars show mean values ±95% confidence intervals. *P<0.05, statistical significance, **P<0.01, high statistical significance. CB, healthy control group; DM, streptozotocin-induced diabetic control rats; DM-ESWT, streptozotocin-induced diabetic rats treated with low-intensity shockwave therapy; ns, not significant.