Efficacy of different spinal nerve roots for neuromodulation of micturition reflex in rats

Jianshu Ni,Xiaohu Wang,Nailong Cao,Jiemin Si,Baojun Gu

doi:10.18632/oncotarget.23950

Jianshu Ni, Xiaohu Wang + Show 3 more

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https://doi.org/10.18632/oncotarget.23950

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Journal: Oncotarget	Publication Date: Jan 4, 2018
Citations: 3	License type: cc-by

Affiliation: Shanghai Jiao Tong University

Abstract

Electrical stimulation of peripheral nerves controlling the bladder is an alternative, nondestructive medical treatment for urinary incontinence and retention. In this study, we aimed to identify the most efficient sensory and motor spinal nerve roots involved in the micturition reflex. Unilateral L5-S2 dorsal and ventral roots were electrically stimulated, and bladder reflex contractions were recorded under isovolumetric conditions. Repeated stimulation of the L6 and S1 dorsal roots not only abolished bladder reflex contractions but also induced a poststimulation inhibitory effect, whereas repeated stimulation of the L5 and S2 dorsal roots had no effect. Only the L6 ventral root directly caused bladder contraction when ventral roots L5-S2 were stimulated in sequence. Upon retrograde tracing using pseudorabies virus (PRV), the sacral parasympathetic nucleus of the L6 segment had more PRV-positive cells than the other segments, though the S1 segment of the dorsal root ganglia had the highest density of PRV-positive neurons. These results suggest the L6 ventral root is most efficient in producing detrusor muscle contraction, and the S1 dorsal root best inhibits the micturition reflex.

Highlights

Electrical stimulation of the sacral spinal nerve is an established therapy for patients with urge incontinence, increased frequency, and urinary retention after failure of first-line pharmacotherapy and was approved by the U.S Food and Drug Administration in the 1990s [1, 2]
We aimed to identify the most efficient sensory and motor spinal nerve roots involved in the micturition reflex
These results suggest the L6 ventral root is most efficient in producing detrusor muscle contraction, and the S1 dorsal root best inhibits the micturition reflex

Summary

Introduction

Electrical stimulation of the sacral spinal nerve is an established therapy for patients with urge incontinence, increased frequency, and urinary retention after failure of first-line pharmacotherapy and was approved by the U.S Food and Drug Administration in the 1990s [1, 2]. Sacral neuromodulation has been used for over two decades, its exact effect on the micturition reflex and its mechanism for improving urinary incontinence and urinary retention have not been completely delineated. Over the past few decades, studies have focused on the effect of neuromodulation on experimentally induced voiding dysfunction via electrical stimulation of the spinal nerves. Bladder activation was observed when electrical stimulation passed through the nerve cuff with electrodes placed on the extradural S2 spinal roots [6]. These studies demonstrated the effect of spinal nerve electrical stimulation on bladder function, the stimulation parameters used and the results obtained varied. Several studies demonstrated that electrical stimulation of the L6-S3 VRTs at a range of frequencies and intensities had no or minimal impact on bladder contraction [7,8,9], which is inconsistent with the positive results demonstrated using sacral anterior root stimulation found by Brindley [10]

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