Animal study to determine the electrode configurations that promote functional gains in the storage and voiding phases of lower urinary tract function as a result of activation of spinal circuits with spinal cord epidural stimulation in injured spine.
Study purpose: The overall objective of the current functional bladder mapping study is to investigate the spinal cord epidural stimulation (scES) efficacy at T13-L2 (level of hypogastric nerve inputs/outputs) that can promote neural control of bladder storage (capacity) and voiding efficiency after spinal cord injury (SCI).
Data collection: The testing paradigm involves stimulation on the T13-L2 segment of the spinal cord to combinations of frequency (5, 10, 30, 45, 60 Hz) and intensity (50, 75, 100, 150, 300 μA) to determine the most effective parameters for storage and efficient emptying of the bladder and bowel. Endpoints include rectal and distal colon pressure activity, external urethral sphincter electromyography (EUS EMG), external anal sphincter electromyography (EAS EMG), bulbospongiosus electromyography in males (bulbo EMG), bladder pressure changes, voiding and drop patterns, volume of voided fluid, and muscle movement thresholds.
Primary conclusion: As found with L5-S1 scES, T13-L2 scES at select frequencies and intensities of stimulation produced an increase in inter-contraction interval in non-injured female rats but a short-latency void in chronic T8 transected rats, as well as reduced rectal activity in all groups. However, with T13-L2 scES, the detrusor pressure during the extended urinary hold remained at a safe, low level and was not elevated as seen with L5-S1 scES, voiding post-transection occurred by increasing bladder activity while also directly inhibiting the external urethral sphincter and increased distal colon activity was also found. Together, the current findings suggest that optimization of scES for bladder and bowel will likely require multiple electrode cohorts at different locations that target circuitries coordinating sympathetic, parasympathetic, and somatic outputs.
Experimental Design: Spinal cord epidural stimulation (scES) mapping at T13-L2 was performed to identify parameters for bladder and bowel storage and/or emptying. Using spinally intact and chronically transected rats of both sexes in acute urethane-anesthetized terminal preparations, scES was systematically applied using a modified Specify 5-6-5 (Medtronic) electrode during bladder filling/emptying cycles while recording bladder and colonic/rectal pressures and external urethral and anal sphincter EMG activity.
Completeness: This dataset is a part of a larger study: Functional mapping with lumbosacral epidural stimulation for restoration of bladder function after spinal cord injury.
Subjects & Samples: A total of 36 female and male Wistar rats were targeted for this mapping study. Half the animals (n=8 females, n=9 males) received a complete spinal cord transection at the T9 spinal level (done 6 weeks prior to terminal mapping study), whereas the intact groups (n=7 females, n=12 males) were not exposed to any surgical manipulation prior to terminal mapping procedures.
Primary vs derivative data: Electrophysiology recordings are done using Spike2 software, which contains the setup for all of the channels being recorded (EUS, EAS, bulbo, 2 cm probe, 10 cm probe, leaks, stim. marker, keyboard input). The primary data folder is organized by the subject IDs. There is no derivative data folder.
Important notes: This dataset is currently undergoing data registration and will be updated once this process is complete.
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