Unmasking the Role of DA in Micturition Function after SCI文献综述

Introduction

Spinal cord injury is defined as damage to the spinal cord that temporarily or permanently causes changes in its function. 96.5% of SCI is traumatic SCI. This kind of injury occurs when an external physical impact, like a motor vehicle injury, fall, violence or sports-related injury, crash the vertebra and protruding bone fragments compress spinal cord and cause acute damage.

Spinal cord injury (SCI) results not only in motor and sensory deficits but also in autonomic dysfunctions. Normal autonomic function is critically dependent on the interaction between supraspinal centers and spinal autonomic components. The disruption of connections between higher brain centers and the spinal cord will cause a broad range of autonomic abnormalities. Including respiratory, cardiovascular, gastrointestinal, urinary and sexual dysfunction. And my project focus on the urinary dysfunction after spinal cord injury.

The function of the micturition reflex is to store urine and then to completely empty urine at appropriate times. Supralumbral spinal cord injure disconnects the brain from the spinal cord. The loss of external urethral sphincter voluntary control results in discoordination between the detrusor and external urethral sphincter (i.e., detrusor sphincter dyssynergia [DSD]). Over time, the bladder becomes “overactive” that means bladder can even be active at low bladder volumes, each wave of involuntary bladder contraction is accompanied by simultaneous contraction of the sphincter. then produce small, intermittent contractions of the detrusor and unwanted leakage. This highly inefficient voiding results in urinary retention with high bladder pressure and renal failure.

Methods

T10 transection

To make an animal model, we gently remove the back part of the T8 vertebra that covers the T10 spinal cord. Then we use blade to completely cut this spinal segment. So we cut the supraspinal control but keep the involuntary bladder reflex. After this operation we take care of those rats and manually express bladder 3 times a day for 3 weeks. And then we do bladder cystometry and external urethral sphincter electromyography.

Bladder cystometry and external urethral sphincter electromyography.

We expose the bladder and EUS, insert a catheter into the bladder wall, 2 electrode on both sides of EUS. Then we place rat in a restraining cage, Connect the electrode to a recording system and bladder catheter to a pressure transducer and microinjection pump. Rats will be infused with saline into bladder after awake. So we will record the signals of bladder pressure, EUS activity and calculate voiding volume.

Preliminary studies