Activation of TRPA1 by luminal stimuli induces EP4-mediated anion secretion in human and rat colon.
Am J Physiol Gastrointest Liver Physiol
; 302(7): G690-701, 2012 Apr.
Article
en En
| MEDLINE
| ID: mdl-22207576
ABSTRACT
In gastrointestinal (GI) physiology, anion and fluid secretion is an important function for host defense and is induced by changes in the luminal environment. The transient receptor potential A1 (TRPA1) channel is considered to be a chemosensor in several sensory tissues. Although the function of TRPA1 has been studied in GI motility, its contribution to the transepithelial ion transport system has rarely been discussed. In the present study, we investigated the secretory effect of the potential TRPA1 agonist allyl isothiocyanate (AITC) in rat and human colon using an Ussing chamber. The mucosal application of AITC (10(-6)-10(-3) M) induced Cl(-) and HCO(3)(-) secretion in a concentration-dependent manner, whereas the serosal application induced a significantly weaker effect. AITC-evoked anion secretion was attenuated by tissue pretreatment with piroxicam and prostaglandin (PG) E(2); however, this secretion was not affected by TTX, atropine, or extracellular Ca(2+) depletion. These experiments indicate that TRPA1 activation induces anion secretion through PG synthesis, independent of neural pathways in the colon. Further analysis also indicates that AITC-evoked anion secretion is mediated mainly by the EP(4) receptor subtype. The magnitude of the secretory response exhibited segmental heterogeneity in rat colon. Real-time PCR analysis showed the segmental difference was corresponding to the differential expression of EP(4) receptor and cyclooxygenase-1 and -2. In addition, RT-PCR, in situ hybridization, and immunohistochemical studies showed TRPA1 expression in the colonic epithelia. Therefore, we conclude that the activation of TRPA1 in colonic epithelial cells is likely involved in the host defense mechanism through rapid anion secretion.
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Canales de Calcio
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Regulación de la Expresión Génica
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Colon
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Canales de Potencial de Receptor Transitorio
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Canales Catiónicos TRPC
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Subtipo EP4 de Receptores de Prostaglandina E
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Proteínas del Tejido Nervioso
Límite:
Aged
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Animals
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Female
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Humans
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Male
Idioma:
En
Revista:
Am J Physiol Gastrointest Liver Physiol
Asunto de la revista:
FISIOLOGIA
/
GASTROENTEROLOGIA
Año:
2012
Tipo del documento:
Article
País de afiliación:
Japón