Bladder and bowel responses to lumbosacral epidural stimulation in uninjured and transected anesthetized rats

Scientific Reports, 2021 · DOI: 10.1038/s41598-021-81822-3 · Published: February 5, 2021

Simple Explanation

This study investigates how electrical stimulation of the spinal cord can affect bladder and bowel function in rats, both with and without spinal cord injuries. Researchers used electrodes to apply stimulation at different frequencies and intensities, observing the effects on bladder and bowel activity. The experiments revealed that specific stimulation parameters can either inhibit or promote bladder and bowel contractions, depending on the neurological condition of the rat. These findings suggest that tailored spinal cord stimulation could be a potential therapy for individuals with spinal cord injuries. A custom-designed electrode array was tested and showed that targeted stimulation over a smaller surface area of the spinal cord could achieve similar urinary effects without causing unwanted movements. This improved selectivity is a promising step toward developing more refined neuromodulation techniques.

Study Duration

Not specified

Participants

33 rats (intact and chronic transected, both sexes) for Medtronic array testing; 5 intact female rats for Micro-Leads array testing

Evidence Level

Not specified

Key Findings

1
Frequency-dependent effects on void volume, micturition, bowel peristalsis, and sphincter activity were observed with spinal cord epidural stimulation (scES), differing based on neurological intactness and sex.
2
In spinally intact rats, high-frequency scES induced a storage-like effect in the bladder, preventing contraction and leading to overflow incontinence, while lower intensities paired with high frequency increased void volume.
3
In transected rats, scES triggered an immediate void regardless of bladder contractions, suggesting injury-induced plasticity in spinal circuits. The custom-designed electrode array showed similar urinary effects over a smaller surface area without concurrent movements.

Research Summary

The study systematically mapped the effects of lumbosacral spinal cord epidural stimulation (scES) on bladder and bowel function in both intact and spinal cord transected rats, identifying frequency-dependent parameters for bladder and bowel inhibition and/or contraction. Results showed that scES can modulate micturition and bowel peristalsis differently depending on the neurological status (intact vs. transected), sex, and stimulation parameters (frequency and intensity). Specifically, high-frequency stimulation in intact rats induced a storage-like effect in the bladder, while in transected rats, it triggered immediate voiding. A custom-designed miniature electrode array demonstrated the potential for selective activation of autonomic nervous system circuitries, achieving urinary effects over a much smaller surface area without causing unwanted movements, indicating a promising neuromodulation approach for individuals with spinal cord injury and other neurological disorders.

Practical Implications

Therapeutic Potential for SCI Patients

The findings suggest that tailored spinal cord stimulation could be developed as a therapeutic intervention for managing bladder and bowel dysfunction in individuals with spinal cord injuries, potentially reducing reliance on catheterization.

Refined Neuromodulation Techniques

The success of the custom-designed electrode array indicates that refined neuromodulation techniques with highly targeted stimulation could minimize unwanted side effects, such as gross motor movements, and improve the precision of autonomic nervous system control.

Understanding Spinal Circuitry

Mapping data provides insights into the location and stimulation parameters needed for specific responses in bladder, sphincter, and colorectal functions, advancing our understanding of the neural circuits involved in these processes.

Study Limitations

1
The use of an anesthetized model may have influenced the interpretation of some responses, such as the lack of bladder contractions in transected males.
2
The Medtronic electrode used for the majority of data collection is large and non-specific, potentially activating broader areas than intended.
3
The fill cycle was driven artificially for expedient mapping, at a supra-physiological rate

Your Feedback

Was this summary helpful?

Back to Spinal Cord Injury