The effect of extracorporeal shock wave on cavernous nerve stimulation-induced intracavernous pressure increase in the diabetic rat
Kuang-Kuo Chen, Luke S. Chang
Department of Urology, Taipei Veterans General Hospital, and Shu-Tien Urological Research Center, National Yang-Ming University, Taiwan
Purpose: Diabetes mellitus (DM) is commonly associated with erectile dysfunction (ED). Low-intensity extracorporeal shock wave therapy (LI-ESWT) has been used to treat patients with ED. However, the pre-clinical investigation of LI-ESWT for ED is still not enough. Therefore, the objective of this study was to investigate the effect of LI-ESW on cavernous nerve (CN) stimulation-induced intracavernous pressure (ICP) increase in the diabetic rat.
Materials and Methods: Male adult Sprague-Dawley rats (250-300 g) were used. Intraperitoneal injection of streptozotocin (STZ) 70 mg/kg was done to induce DM in the rats. Only rats with blood glucose levels of greater than 300 mg/dl (hyperglycemia) three days after STZ injection were used. Three groups of experimental animals were designed as following: 1)ESW (0.05 mJ/mm2) to penile shaft, 800 shocks twice a week for 2 weeks, 2)ESW (0.05 mJ/mm2) to penile shaft, 1200 shocks twice a week for 2 weeks, and 3)application of probe without ESW to penile shaft twice a week for 2 weeks as a sham control. A 26-gauge needle was inserted into the corpus cavernosum to monitor the ICP. The CN was electrically stimulated with parameters (5 and 7.5 V, 20 Hz, 2 ms, 1 minute) on the 14th day after 2-week ESW in each of the three group rats. The amount of ICP increase was the difference between the peak ICP and resting ICP. Wilcoxon signed rank test and Mann-Whitney U test were used for statistical analysis.
Results: There was a significant increase of ICP from resting 5.3 ± 0.8 mmHg, 12.0 ± 1.9 mmHg and 5.2 ± 1.3 mmHg to a peak at 74.8 ± 6.5 mmHg (p=0.027), 81.0 ± 6.1 mmHg (p=0.028) and 45.8 ± 6.2 mmHg (p=0.028) after CN stimulation with parameters 7.5 V in group 1, 2 and 3 rats, respectively. The corresponding amount of ICP increase were 69.5 ± 6.9 mmHg, 69.0 ± 5.4 mmHg and 40.7 ± 5.0 mmHg in group 1, 2 and 3 rats, respectively. There was a significant greater amount of ICP increase in the group 1 (p=0.015) and group 2 rats (p=0.015) as compared with group 3 rats (sham control), respectively.
Conclusions: The results suggest that low-intensity extracorporeal shock wave may have a significant enhancing effect on cavernous nerve stimulation-induced intracavernous pressure increase in the diabetic rat.