A time-course study of urodynamic analyses in rat models with dopaminergic depletion induced through unilateral and bilateral 6-hydroxydopamine injections

J Formos Med Assoc. 2023 Mar;122(3):239-248. doi: 10.1016/j.jfma.2022.09.009. Epub 2022 Sep 28.

Abstract

Background: Bladder dysfunction is a common non-motor disorder in Parkinson's disease (PD). This study attempted to determine the bladder dysfunction with disease progression in the PD rat model produced from unilateral/bilateral injections of 6-hydroxydopamine (6-OHDA).

Methods: Cystometrographic (CMG) and external urethral sphincter electromyographic (EUS-EMG) measurements were scheduled in a time-course manner to determine the disease timing, onset, and severity. Animals were allotted into normal control, unilateral, bilateral 6-OHDA injected groups and subjected to scheduled CMG, EUS-EMG analyses at weeks 1, 2, and 4.

Results: The urodynamic results concluded that voiding efficiency (VE) was reduced in both unilateral and bilateral PD rats at all-time points. VE had decreased from 57 ± 11% to 31 ± 7% in unilateral PD rats and in bilateral PD rats, a decreased VE of 20 ± 6% was observed compared to control and unilateral PD rats. The EMG results in unilateral PD rats indicated declines in bursting period (BP) (3.78-2.94 s), active period (AP) (93.38-88.75 ms), and silent period (SP) (161.62-114.30 ms). A sudden reduction was noticed in BP (3.62-2.82 s), AP (92.21-86.01 ms), and SP (128.61-60.16 ms) of bilateral PD rats than in control and unilateral PD rats. Histological evidence exhibited a progressive dopaminergic neurons (DA) depletion in the substantia nigra (SN) region in 6-OHDA lesioned rats.

Conclusion: The experimental outcomes strongly implied that significant variations in bladder function and VE decline were due to the depletion of DA neurons in the SN region of the brain.

Keywords: 6-hydroxydopamine; Bladder dysfunction; Cystometric measurements; Parkinson's disease; Voiding efficiency.

MeSH terms

  • Animals
  • Disease Models, Animal
  • Dopamine
  • Dopaminergic Neurons
  • Oxidopamine
  • Parkinson Disease*
  • Rats
  • Rats, Sprague-Dawley
  • Urodynamics*

Substances

  • Oxidopamine
  • Dopamine