title: Descending facilitation of spinal NMDA-dependent reflex potentiation from pontine tegmentum in rats.
abstract: This study was conducted to investigate whether dorsolateral pontine tegmentum stimulation modulates spinal reflex potentiation (SRP) and whether serotonergic neurotransmission is involved in such a modulation. Reflex activities of the external urethra sphincter (EUS) electromyogram in response to a test stimulation (TS; 1/30 Hz) or repetitive stimulation (RS; 1 Hz) on the pelvic afferent nerve in 35 anesthetized rats were recorded with/without synchronized train pontine stimulation (PS; 300 Hz, 30 ms) and/or intrathecal administrations of 10 microl of 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo (F) quinoxaline (NBQX; 100 microM), d-2-amino-5-phosphonovalerate (APV; 100 microM), N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl) cyclohexanecarboxamide trihydrochloride (WAY 100635; 100 microM), and 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT; 100 microM). The TS evoked a single action potential (1.00 +/- 0.00 spikes/stimulation), while the RS produced a long-lasting SRP (16.12 +/- 1.59 spikes/stimulation) that was abolished by APV (1.57 +/- 0.29 spikes/stimulation) and was attenuated by NBQX (7.42 +/- 0.57 spikes/stimulation). Synchronized train PS with RS (PS+RS) produced facilitation in RS-induced SRP (25.17 +/- 2.21 spikes/stimulation). Intrathecal WAY 100635 abolished the facilitation in SRP as a result of the synchronized PS (14.66 +/- 1.58 spikes/stimulation). On the other hand, intrathecal 8-OH-DPAT elicited facilitation in the RS-induced SRP (25.16 +/- 1.05 spikes/stimulation) without synchronized PS. Our findings suggest that dorsolateral pontine tegmentum may modulate N-methyl-d-aspartic acid-dependent SRP via descending serotonergic neurotransmission. This descending modulation may have physiological/pharmacological relevance in the neural controls of urethral closure.
authors.affiliation: Department of Obstetrics and Gynecology, Chung-Shan Medical University Hospital, Taiwan.
authors.forename: Gin-Den
authors.initials: GD
authors.lastname: Chen
authors.forename: Hsien-Yu
authors.initials: HY
authors.lastname: Peng
authors.forename: Kwong-Chung
authors.initials: KC
authors.lastname: Tung
authors.forename: Chen-Li
authors.initials: CL
authors.lastname: Cheng
authors.forename: Yi-Jui
authors.initials: YJ
authors.lastname: Chen
authors.forename: Jiuan-Miaw
authors.initials: JM
authors.lastname: Liao
authors.forename: Yu-Cheng
authors.initials: YC
authors.lastname: Ho
authors.forename: Shwu-Fen
authors.initials: SF
authors.lastname: Pan
authors.forename: Mei-Jung
authors.initials: MJ
authors.lastname: Chen
authors.forename: Tzer-Bin
authors.initials: TB
authors.lastname: Lin
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D005260:Female; D017774:Long-Term Potentiation / Q000502:physiology*; D016202:N-Methylaspartate / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology; D010879:Piperazines / Q000494:pharmacology; D011149:Pons / Q000502:physiology*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000187:drug effects / Q000502:physiology; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013127:Spinal Nerves / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014521:Urethra / Q000294:innervation
chemical_list: D010879:Piperazines; D011725:Pyridines; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D016202:N-Methylaspartate; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin