Descending facilitation of spinal NMDA-dependent reflex potentiation from pontine tegmentum in rats.
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.
Chen
Gin-Den
GD
Department of Obstetrics and Gynecology, Chung-Shan Medical University Hospital, Taiwan.
Peng
Hsien-Yu
HY
Tung
Kwong-Chung
KC
Cheng
Chen-Li
CL
Chen
Yi-Jui
YJ
Liao
Jiuan-Miaw
JM
Ho
Yu-Cheng
YC
Pan
Shwu-Fen
SF
Chen
Mei-Jung
MJ
Lin
Tzer-Bin
TB
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
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