Change of Neuropeptides of Bladder Afferents after Intravesical Electrical Stimulation in Spinalized Rat / 대한비뇨기과학회지

ABSTRACT

PURPOSE: The clinical benefits of intravesical electrical stimulation (IVES), in patients with increased residual urine or reduced bladder capacity, have been reported. However, studies on the underlying mechanism of IVES have been limited to the Adelta afferent in healthy rats. This study investigated the changes in the calcitonin gene- related peptide (CGRP) and substance P (SP) expressions, in the lumbosacral dorsal root ganglia (DRG) and the bladder of spinalized rats, to determine the effect of IVES on the C fiber afferent nerve. MATERIALS AND METHODS: Forty Sprague-Dawley rats were divided into normal controls (n=10); IVES treated normal rats (n=10); spinalized rats (n=10) and IVES treated spinalized rats (n=10). The IVES was performed for 2 weeks (5 days a week), 3 weeks after the spinalization in the spinalized animals. All animals had their DRG removed at the lumbosacral (L5-S1) level. Changes in the CGRP and SP, at the DRG and bladder, were measured by western-blot analysis. RESULTS: The relative density of the CGRP and SP following spinalization was significantly higher than those in the controls in both the DRG and the bladder. However, IVES in the spinalized rat significantly decreased the relative density of the SP, in both the DRG and the bladder, compared to the rats with spinalization alone. IVES in the spinalized rats significantly decreased the relative density of the CGRP, in the DRG only, compared to the rats with spinalization. CONCLUSIONS: IVES significantly reduced the CGRP and SP levels in the DRG of spinalized rats, but only the SP levels in the bladder. CGRP and SP are the main factors contributing to the hyper-excitability of the micturition reflex following spinal cord injury. These results suggest that the bladder C fiber afferents are also involved in modulating the micturition reflex with IVES.