Impaired micturition reflex caused by acute selective dorsal or ventral root(s) rhizotomy in anesthetized rats

Purpose: To clarify the contributions of parasympathetic inputs and outputs to the micturition reflex. Materials and Methods: Intra-vesical pressure (IVP), external urethral sphincter electromyogram (EMG), pelvic afferent nerve activities (PANA), and pelvic efferent nerve activities (PENA) as well as the time-derived IVP (dIVP, an index of bladder contractility) were evaluated in intact and acute dorsal or ventral root(s) rhizotomized (DRX and VRX, respectively) rats. Results: In DRX rats, when compared with that in intact stage, the voiding frequency was decreased (75 ± 15% of intact, P <0.05, n = 8), while the threshold pressure to trigger voiding contractions was significantly increased (187 ± 75% of intact, P <0.05, n = 8). In addition, several insufficient contractions (5.3 ± 3.5 contractions/voiding, P <0.05, n = 8) occurred in ahead of each voiding contraction. On the other hand, in VRX rats, the peak and rebound IVP were significantly decreased (90 ± 3.5% and 75 ± 11.3% of intact, P <0.01, n = 8), while the threshold pressure was not affected (102 ± 11% of intact, P = NS, n = 8). The time-derived parameters were significantly decreased in VRX (peak dIVP, 78 ± 10.2%, rebound dIVP, 75 ± 15.6%, minimal dIVP, 68 ± 14% of intact, P <0.01, n = 8) but only peak dIVP was decreased (85 ± 11% of intact, P <0.01, n = 8) in DRX rats. Conclusion: Acute selective DRX and VRX rat can be an animal model to investigate peripheral neural control in micturition functions.