Nicotine-activated descending facilitation on spinal NMDA-dependent reflex potentiation from pontine tegmentum in rats

Shwu Fen Pan, Hsien Yu Peng, Chi Chung Chen, Mei Jung Chen, Shin Da Lee, Chen Li Cheng, Jyh Cherng Shyu, Jiuan Miaw Liao, Gin Den Chen, Tzer Bin Lin

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

This study was conducted to investigate the possible neurotransmitter that activates the descending pathways coming from the dorsolateral pontine tegmentum (DPT) to modulate spinal pelvic-urethra reflex potentiation. External urethra sphincter electromyogram (EUSE) activity in response to test stimulation (TS, 1/30 Hz) and repetitive stimulation (RS, 1 Hz) on the pelvic afferent nerve of 63 anesthetized rats were recorded with or without microinjection of nicotinic cholinergic receptor (nAChR) agonists, ACh and nicotine, to the DPT. TS evoked a baseline reflex activity with a single action potential (1.00 ± 0.00 spikes/stimulation, n = 40), whereas RS produced a long-lasting reflex potentiation (16.14 ± 0.96 spikes/stimulation, n = 40) that was abolished by D-2-amino-5-phosphonovaleric acid (1.60 ± 0.89 spikes/stimulation, n = 40) and was attenuated by 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo (F) quinoxaline (7.10 ± 0.84 spikes/stimulation, n = 40). ACh and nicotine microinjections to DPT both produced facilitation on the RS-induced reflex potentiation (23.57 ± 2.23 and 28.29 ± 2.36 spikes/stimulation, P <0.01, n = 10 and 20, respectively). Pretreatment of selective nicotinic receptor antagonist, chlorisondamine, reversed the facilitation on RS-induced reflex potentiation caused by nicotine (19.41 ± 1.21 spikes/stimulation, P <0.01, n = 10) Intrathecal WAY-100635 and spinal transection at the T 1 level both abolished the facilitation on reflex potentiation resulting from the DPT nicotine injection (12.86 ± 3.13 and 15.57 ± 1.72 spikes/stimulation, P <0.01, n = 10 each). Our findings suggest that activation of nAChR at DPT may modulate N-methyl-D-aspartic acid-dependent reflex potentiation via descending serotonergic neurotransmission. This descending modulation may have physiological/ pathological relevance in the neural controls of urethral closure.

Original languageEnglish
JournalAmerican Journal of Physiology - Renal Physiology
Volume294
Issue number5
DOIs
Publication statusPublished - May 2008
Externally publishedYes

Keywords

  • Acetylcholine
  • Intrathecal
  • N-methyl-D-aspartic acid
  • Rats
  • Serotonin
  • Spinal reflex potentiation
  • WAY-100635

ASJC Scopus subject areas

  • Physiology
  • Urology

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