Effects of selective unilateral dorsal root(s) rhizotomy on micturition reflex in anesthetized rats.
OBJECTIVE
To clarify the contributions of sensory inputs and glutamate transmissions to the spinal micturition reflex.


METHODS
Cystometrogram and external urethral sphincter electromyogram activities evaluated the L6 and/or S1 levels.


RESULTS
Changes in intravesicular pressure (IVP) in response to saline infusion (0.1 ml/min) were found after unilateral dorsal root rhizotomy at the L6 level, which showed significant increases in threshold pressure (rhizotomized vs. control: 14.25 +/- 0.82 vs. 8.40 +/- 0.69 cmH(2)O, P < 0.01, n = 28), post-voiding pressure (7.66 +/- 0.56 vs. 5.42 +/- 0.52 cmH(2)O, P < 0.01, n = 28), holding duration (135.06 +/- 23.6 vs. 77.73 +/- 13.56 sec, P < 0.05, n = 28), and inter-contraction interval (140.62 +/- 23.29 vs. 82.40 +/- 13.57 sec, P < 0.05, n = 28). Several (mean = 2.32 +/- 1.31 vs. 0.12 +/- 0.21, P < 0.01, n = 28, P < 0.01, n = 28) non-voiding contractions with gradual increase in IVP were found ahead of voiding contraction after rhizotomy. An additional dorsal root rhizotomy at the ipsilateral S1 level caused further increases in urodynamic parameters (threshold pressure, 18.18 +/- 1.67 cmH(2)O, P < 0.01; post-voiding pressure 8.07 +/- 0.96 cmH(2)O, P < 0.01; holding duration, 211.44 +/- 42.54 sec, P < 0.01; inter-contraction interval, 264.2 +/- 59.99 sec, P < 0.05; non-voiding contractions, 4.41 +/- 2.12, P < 0.01, n = 7). Intrathecal glutamate (100 microM, 10 microl) ameliorated all the pathological conditions induced by unilateral dorsal root rhizotomy at the L6 level in a dose dependent manner (ED(50) = 1.25 +/- 10(-5)). Intrathecal CNQX (6-cyano-7-nitroquinoxaline-2,3-dione; 100 microM, 10 microl) and APV (D-2-amino-5-phosphonovaleric acid; 100 microM, 10 microl) injections after rhizotomy at the L6 level induced disturbances similar to that caused by an additional rhizotomy at ipsilateral S1 level. Wherease, glutamate (100 microM, 10 microl) reversed the disturbances caused by CNQX but showed no effect on that by APV.


CONCLUSIONS
Acute partial sensory deprivation caused acute impaired micturition reflex in rat models. In addition, glutamatergic NMDA and AMPA receptors are important for mediating these impairments in micturition reflex.
Tsai
Ming-Cheng
MC
Department of Pharmacology, National Taiwan University, Taipei, Taiwan.
Tang
Chih-Yung
CY
Chang
Ya-Ting
YT
Cheng
Chen-Li
CL
Liao
Jiuan-Miaw
JM
Lee
Shin-Da
SD
Pan
Shwu-Fen
SF
Chen
Mei-Jung
MJ
Huang
Pei-Chen
PC
Lin
Tzer-Bin
TB
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004576:Electromyography; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D018698:Glutamic Acid / Q000008:administration & dosage / Q000494:pharmacology; D007278:Injections, Spinal; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D012018:Reflex / Q000502:physiology*; D019051:Rhizotomy; D013126:Spinal Nerve Roots / Q000502:physiology*; D014554:Urination / Q000502:physiology*; D014563:Urodynamics / Q000187:drug effects / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D015763:2-Amino-5-phosphonovalerate