Dynamic pelvic-pudendal reflex plasticity mediated by glutamate in anesthetized rats.
Reflex plasticity between pelvic afferent nerve (PAN) and pudendal efferent nerve (PEN), as well as external-urethral sphincter (EUS) activity was examined in anesthetized rats. A progressive increase in the number of evoked action potentials per stimulus occurred in PEN and EUS activity when PAN was repetitively stimulated (1 Hz). This potentiation in pelvic-pudendal reflex (PPR) activity induced by repetitive stimulation was abolished by APV (D-2-amino-5-phosphonoraleric acid, i.t. 100 microM, 2-5 microl) and attenuated by the NBQX (2, 3-dihydroxy-6-nitro-7-sulfamoyl-benzo (F) quinoxaline, i.t. 20 microM, 2-5 microl) but was not affected by the presence of bicuculline (i.t. 10 microM, 2-5 microl). The duration of contraction wave of intra-urethral pressure (IUP) elicited by a single electric shock was elongated by potentiated PPR, while the peak pressure was not affected. Both intrathecal application of glutamate (i.t. 0.1 mM, 2-5 microl) and NMDA (N-methyl-D-aspartic acid, i.t. 0.1 mM, 2-5 microl) induced spontaneous repetitive (0.31+/-0.02 Hz) burst discharges in PEN and EUSE and produced small contraction wave in IUP, which is similar to the high frequency oscillation phase during a voiding cycle of urinary bladder in rats. All these results demonstrate that repetitive stimulation of PAN can induce a distinct and long-lasting modulation in PPR activity and this change may be physiologically relevant in urinary continence.
Lin
T-B
TB
Department of Physiology, College of Medicine, Chung-Shan Medical University, No. 110, Chang-Kuo North Road, 1st Section, Taichung, Taiwan. tblin@mercury.csmu.edu.tw
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000758:Anesthesia; D000818:Animals; D001640:Bicuculline / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D018698:Glutamic Acid / Q000494:pharmacology*; D007796:Laminectomy / Q000379:methods; D016202:N-Methylaspartate / Q000494:pharmacology; D009434:Neural Pathways / Q000187:drug effects*; D009473:Neuronal Plasticity / Q000187:drug effects; D010388:Pelvis / Q000502:physiology*; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000187:drug effects* / Q000502:physiology; D014521:Urethra / Q000187:drug effects* / Q000294:innervation
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D011810:Quinoxalines; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; D018698:Glutamic Acid; C017069:bicuculline methiodide; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; D001640:Bicuculline