W1374 Excitation of Neurons in the Enteric Nervous System (ENS), Degranulation of Enteric Mast Cells and Direct Action On Enterocytes Underlie Stimulatory Action of Bradykinin (Bk) On Mucosal Secretion in Guinea-Pig Small Intestine

2008 ◽  
Vol 134 (4) ◽  
pp. A-691
Author(s):  
Guo-Du Wang ◽  
Xiyu Wang ◽  
Fie Zou ◽  
Yun Xia ◽  
Sumei Liu ◽  
...  
2003 ◽  
Vol 459 (1) ◽  
pp. 27-39 ◽  
Author(s):  
Sumei Liu ◽  
Hong-Zhen Hu ◽  
Chuanyun Gao ◽  
Na Gao ◽  
Guodu Wang ◽  
...  

2014 ◽  
Vol 307 (7) ◽  
pp. G719-G731 ◽  
Author(s):  
Guo-Du Wang ◽  
Xi-Yu Wang ◽  
Sumei Liu ◽  
Meihua Qu ◽  
Yun Xia ◽  
...  

Mast cells express the substance P (SP) neurokinin 1 receptor and the calcitonin gene-related peptide (CGRP) receptor in guinea pig and human small intestine. Enzyme-linked immunoassay showed that activation of intramural afferents by antidromic electrical stimulation or by capsaicin released SP and CGRP from human and guinea pig intestinal segments. Electrical stimulation of the afferents evoked slow excitatory postsynaptic potentials (EPSPs) in the enteric nervous system. The slow EPSPs were mediated by tachykinin neurokinin 1 and CGRP receptors. Capsaicin evoked slow EPSP-like responses that were suppressed by antagonists for protease-activated receptor 2. Afferent stimulation evoked slow EPSP-like excitation that was suppressed by mast cell-stabilizing drugs. Histamine and mast cell protease II were released by 1) exposure to SP or CGRP, 2) capsaicin, 3) compound 48/80, 4) elevation of mast cell Ca2+ by ionophore A23187, and 5) antidromic electrical stimulation of afferents. The mast cell stabilizers cromolyn and doxantrazole suppressed release of protease II and histamine when evoked by SP, CGRP, capsaicin, A23187, electrical stimulation of afferents, or compound 48/80. Neural blockade by tetrodotoxin prevented mast cell protease II release in response to antidromic electrical stimulation of mesenteric afferents. The results support a hypothesis that afferent innervation of enteric mast cells releases histamine and mast cell protease II, both of which are known to act in a diffuse paracrine manner to influence the behavior of enteric nervous system neurons and to elevate the sensitivity of spinal afferent terminals.


2001 ◽  
Vol 440 (3) ◽  
pp. 299-310 ◽  
Author(s):  
Hong-Zhen Hu ◽  
Na Gao ◽  
Zhong Lin ◽  
Chuanyun Gao ◽  
Sumei Liu ◽  
...  

1994 ◽  
Vol 266 (3) ◽  
pp. G403-G416 ◽  
Author(s):  
P. R. Wade ◽  
H. Tamir ◽  
A. L. Kirchgessner ◽  
M. D. Gershon

The effects of anti-idiotypic antibodies (alpha-id) that recognize serotonin [5-hydroxytryptamine (5-HT)] receptors on myenteric neurons of the guinea pig small intestine were characterized electrophysiologically, and alpha-id binding sites were located immunocytochemically. Initial applications of the alpha-id mimicked each of three actions of 5-HT: a rapid depolarization, associated with a fall in input resistance (Rin), which was inhibited by the 5-HT3 antagonists tropisetron (> or = 1 microM) and renzapride (100 microM); a slow membrane depolarization, associated with increased Rin, that was inhibited by the 5-HT1P antagonist renzapride but was unaffected by a 5-HT4 blocking concentration of tropisetron (10 microM); and a hyperpolarization, associated with decreased Rin, that was antagonized by the 5-HT1A inhibitor NAN-190. Cross-desensitization was observed between responses to 5-HT and the alpha-id. After exposure to the alpha-id, subsequent responses to the alpha-id, 5-HT, and stimulus-evoked slow excitatory postsynaptic potentials were antagonized; however, responses to carbachol and substance P were unaffected. The alpha-id thus specifically inhibits the effects of endogenously released and exogenously applied 5-HT. The alpha-id bound to sites on myenteric and submucosal neurons and a subepithelial nerve plexus. Binding of the alpha-id was blocked by 5-HT1P-, 5-HT3-, and 5-HT4-specific antagonists. We concluded that the alpha-id binds selectively to all known subtypes of 5-HT receptor in the enteric nervous system and is thus useful for investigating the gastrointestinal function of 5-HT.


2005 ◽  
Vol 289 (3) ◽  
pp. G614-G626 ◽  
Author(s):  
Guo-Du Wang ◽  
Xi-Yu Wang ◽  
Hong-Zhen Hu ◽  
Xiu-Cai Fang ◽  
Sumei Liu ◽  
...  

Actions of ANG II on electrical and synaptic behavior of enteric neurons in the guinea pig small intestine were studied. Exposure to ANG II depolarized the membrane potential and elevated neuronal excitability. The number of responding neurons was small, with responses to ANG II in 32% of submucosal neurons and 25% of myenteric neurons. Hyperpolarizing responses were evoked by ANG II in 45% of the neurons. The hyperpolarizing responses were suppressed by α2-noradrenergic receptor antagonists, which suggested that the hyperpolarizing responses reflected stimulation of norepinephrine release from sympathetic neurons. Exposure to ANG II enhanced the amplitude and prolonged the duration of noradrenergic inhibitory postsynaptic potentials and suppressed the amplitude of both fast and slow excitatory postsynaptic potentials. The selective ANG II1 receptor (AT1R) antagonists, ZD-7115 and losartan, but not a selective AT2R antagonist (PD-123319), suppressed the actions of ANG II. Western blot analysis and RT-PCR confirmed expression of AT1R protein and the mRNA transcript for the AT1R in the enteric nervous system. No expression of AT2R protein or mRNA was found. Immunoreactivity for AT1R was expressed by the majority of neurons in the gastric antrum and small and large intestine. AT1R immunoreactivity was coexpressed with calbindin, choline acetyltransferase, calretinin, neuropeptide Y, and nitric oxide synthase in subpopulations of neurons. The results suggest that formation of ANG II might have paracrine-like actions in the enteric nervous system, which include alterations in neuronal excitability and facilitated release of norepinephrine from sympathetic postganglionic axons. The enhanced presence of norepinephrine is expected to suppress fast and slow excitatory neurotransmission in the enteric microcircuits and to suppress neurogenic mucosal secretion.


Sign in / Sign up

Export Citation Format

Share Document