Glutamate is released from capsaicin-sensitive primary afferent fibers: An in vitro superfusion study with on-line monitoring method

1992 ◽  
Vol 17 ◽  
pp. 95
Author(s):  
Mutsuaki Ueda ◽  
Yasushi Kuraishi ◽  
Masamichi Satoh
Keyword(s):  
Monitoring Method ◽  
Primary Afferent ◽  
Afferent Fibers ◽  
In Vitro Superfusion ◽  
Primary Afferent Fibers ◽  
On Line

Acute and neonatal capsaicin treatment inhibit jejunal amino acid absorption through a Na+-dependent mechanism

1997 ◽  
Vol 272 (4) ◽  
pp. G815-G821 ◽  
Author(s):  
K. A. Barada ◽  
S. S. Dika ◽  
S. F. Atweh ◽  
N. E. Saade ◽  
C. F. Nassar
Keyword(s):  
Amino Acid ◽  
Intestinal Epithelial ◽  
Primary Afferent ◽  
Acid Absorption ◽  
Amino Acid Absorption ◽  
Afferent Fibers ◽  
Dependent Component ◽  
Primary Afferent Fibers

It has recently been shown that capsaicin inhibits alanine absorption in rat jejunum via mechanisms that involve intestinal capsaicin-sensitive primary afferent (CSPA) fibers. This study provides further evidence that the effect of capsaicin is neurally mediated and demonstrates that CSPA fibers regulate Na+-dependent amino acid absorption. In vivo, basal alanine absorption in rats neonatally treated with capsaicin was reduced by 35% below control. Furthermore, intraluminal perfusion of 400 microM capsaicin reduced jejunal alanine absorption by 31% in sham rats but had no significant effect in rats neonatally treated with capsaicin. In vitro, capsaicin significantly reduced uptake of alanine and proline by jejunal strips but had no effect on uptake of lysine. Tetrodotoxin (0.2 microM) partially blocked the effects of capsaicin but did not itself affect alanine absorption. Capsaicin reduced unidirectional mucosal-to-serosal alanine (1 mM) influx by 33%, an effect that becomes significant after 5 min of preincubation with capsaicin. Neonatal capsaicin treatment reduced basal alanine influx in jejunal strips by 37%; however, preincubation of these strips with capsaicin had no significant effect. Kinetic analysis of alanine steady-state uptake and influx by jejunal strips incubated with capsaicin revealed that capsaicin reduced the Na+-dependent component of alanine influx into intestinal epithelial cells. Long-term sensory denervation by capsaicin also decreased the Na+-dependent component of alanine absorption. These data suggest that intestinal capsaicin-sensitive primary afferent fibers regulate Na+-dependent amino acid absorption.

Involvement of capsaicin-sensitive primary afferent fibers in regulation of jejunal alanine absorption

1995 ◽  
Vol 268 (4) ◽  
pp. G695-G699 ◽  
Author(s):  
C. F. Nassar ◽  
K. A. Barada ◽  
L. E. Abdallah ◽  
W. S. Hamdan ◽  
A. M. Taha ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
Dependent Manner ◽  
Primary Afferent ◽  
In Vivo Experiments ◽  
Afferent Fibers ◽  
Cervical Vagotomy ◽  
Primary Afferent Fibers

Capsaicin-sensitive primary afferent fibers (CSPA) in the small intestine regulate many functions through the release of peptides and neurotransmitters. This study was undertaken to assess the role of CSPA in the regulation of jejunal alanine absorption in the rat. In a series of in vivo experiments, the effects of the sensory neurotoxin capsaicin on small intestinal alanine absorption were evaluated. In vitro experiments were also done to study its effects on alanine uptake by isolated jejunal strips and mucosal scrapings. Jejunal alanine absorption was reduced by 27% when capsaicin (160 and 800 microM) was perfused intraluminally and by 21% when it was applied topically to the cervical vagi. On the other hand, bilateral cervical vagotomy and reversible block of vagal CSPA increased alanine absorption by 29 and 41%, respectively. In vitro, capsaicin reduced alanine uptake by intestinal strips in a dose-dependent manner. Maximal inhibition (36.5%) occurred at 400 microM with the mean ineffective concentration at 87 microM. Alanine uptake by jejunal mucosal scrapings, however, was decreased only by 6.7% when incubated with 1,600 microM capsaicin. These data suggest that vagal CSPA exerts a tonic inhibitory effect on alanine absorption and that capsaicin's inhibitory effect on alanine absorption is mediated largely by the capsaicin-sensitive afferent fibers.

scholarly journals Opioid Actions in Primary-Afferent Fibers—Involvement in Analgesia and Anesthesia

2011 ◽  
Vol 4 (2) ◽  
pp. 343-365 ◽  
Author(s):  
Eiichi Kumamoto ◽  
Kotaro Mizuta ◽  
Tsugumi Fujita
Keyword(s):  
Primary Afferent ◽  
Afferent Fibers ◽  
Primary Afferent Fibers

scholarly journals Functional Interactions between Tumor and Peripheral Nerve: Changes in Excitability and Morphology of Primary Afferent Fibers in a Murine Model of Cancer Pain

2001 ◽  
Vol 21 (23) ◽  
pp. 9367-9376 ◽  
Author(s):  
David M. Cain ◽  
Paul W. Wacnik ◽  
Michelle Turner ◽  
Gwen Wendelschafer-Crabb ◽  
William R. Kennedy ◽  
...  
Keyword(s):  
Peripheral Nerve ◽  
Cancer Pain ◽  
Murine Model ◽  
Primary Afferent ◽  
Functional Interactions ◽  
Afferent Fibers ◽  
Primary Afferent Fibers

Ultrastructural Analysis of Ectopic Synaptic Boutons Arising From Peripherally Regenerated Primary Afferent Fibers

1999 ◽  
Vol 81 (4) ◽  
pp. 1636-1644 ◽  
Author(s):  
H. Richard Koerber ◽  
Karoly Mirnics ◽  
Anahid M. Kavookjian ◽  
Alan R. Light
Keyword(s):  
Dorsal Horn ◽  
Sensory Neurons ◽  
Ultrastructural Analysis ◽  
Peripheral Stimulus ◽  
Primary Sensory Neurons ◽  
Superficial Dorsal Horn ◽  
Primary Afferent ◽  
Afferent Fibers ◽  
Primary Afferent Fibers ◽  
Synaptic Boutons

Ultrastructural analysis of ectopic synaptic boutons arising from peripherally regenerated primary afferent fibers. The central axons of peripherally regenerated Aβ primary sensory neurons were impaled in the dorsal columns of α-chloralose-anesthetized cats 9–12 mo after axotomy. The adequate peripheral stimulus was determined, and the afferent fibers intracellularly stimulated while simultaneously recording the resulting cord dorsum potentials (CDPs). Fibers that successfully had reinnervated the skin responded to light tactile stimulation, and evoked CDPs that suggested dorsally located boutons were stained intracellularly with horseradish peroxidase (HRP). Two HRP-stained regenerated Aβ afferent fibers were recovered that supported large numbers of axon collaterals and swellings in laminae I, IIo, and IIi. Sections containing the ectopic collateral fibers and terminals in the superficial dorsal horn were embedded in plastic. Analyses of serial ultrathin sections revealed that ectopic projections from both regenerated fibers supported numerous synaptic boutons filled with clear round vesicles, a few large dense core vesicles (LDCVs) and several mitochondria (>3). All profiles examined in serial sections (19) formed one to three asymmetric axo-dendritic contacts. Unmyelinated portions of ectopic fibers giving rise to en passant and terminal boutons often contained numerous clear round vesicles. Several boutons (47%) received asymmetric contacts from axon terminals containing pleomorphic vesicles. These results strongly suggest that regenerated Aβ fibers activated by light tactile stimuli support functional connections in the superficial dorsal horn that have distinct ultrastructural features. In addition, the appearance of LDCVs suggests that primary sensory neurons are capable of changing their neurochemical phenotype.

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