The effect of intravesical electrical stimulation on bladder function and synaptic neurotransmission in the rat spinal cord after spinal cord injury.
OBJECTIVE
To investigate the effects of intravesical electrical stimulation (IVES) on bladder function and synaptic neurotransmission in the lumbosacral spinal cord in the spinalized rat, as the clinical benefits of IVES in patients with increased residual urine or reduced bladder capacity have been reported but studies on the mechanism of IVES have mainly focused on bladder A delta afferents in central nervous system-intact rats.


METHODS
In all, 30 female Sprague-Dawley rats were divided equally into three groups: normal control rats, sham-stimulated spinalized rats and IVES-treated spinalized rats. IVES was started 5 weeks after spinal cord injury (SCI) and was performed 20 min a day for 5 consecutive days. At 7 days after IVES, conscious filling cystometry was performed. Sections from the L6 and S1 spinal cord segments were examined for n-methyl-d-aspartic acid receptor 1 (NMDAR1) subunit and gamma-aminobutyric acid (GABA) immunoactivity.


RESULTS
In IVES-treated spinalized rats, the number and maximal pressure of nonvoiding detrusor contractions were significantly less than in sham-stimulated spinalized rats. The mean maximal voiding pressure was also lower in IVES-treated than in sham-stimulated spinalized rats. IVES significantly reduced the interval between voiding contractions compared with the untreated spinalized rats. There was an overall increase in NMDAR1 immunoactivity after SCI, which was significantly lower in IVES-treated spinalized rats. Immunoactivity of GABA after SCI was significantly lower than in the control group and was significantly higher in IVES-treated spinalized rats.


CONCLUSIONS
Our results suggest that IVES might affect voiding contractions in addition to inhibiting C-fibre activity and that IVES seems to have a more complex effect on the bladder control pathway. For synaptic neurotransmission in the spinal cord, IVES could possibly shift the balance between excitation and inhibition towards inhibition.
Hong
Chang Hee
CH
Departments of Urology, Yonsei University College of Medicine, Seoul, Korea.
Lee
Hye-young
HY
Jin
Mei Hua
MH
Noh
Ji Yeun
JY
Lee
Bong Hee
BH
Han
Sang Won
SW
D000818:Animals; D004599:Electric Stimulation Therapy / Q000379:methods*; D005260:Female; D007150:Immunohistochemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D009435:Synaptic Transmission / Q000502:physiology*; D001743:Urinary Bladder / Q000503:physiopathology*; D014554:Urination / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D016194:Receptors, N-Methyl-D-Aspartate; D005680:gamma-Aminobutyric Acid