• Guang-Yin Xu, John H Winston, Mohan Shenoy, Huaizhi Yin, Swaroop Pendyala, and Pankaj Jay Pasricha.
• Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas 77555, USA.
• Gastroenterology. 2007 Oct 1;133(4):1282-92.

Background & AimsThe neurobiologic basis of pancreatic hyperalgesia in chronic pancreatitis (CP) is understood poorly and there is a need to identify novel therapeutic targets. Our aim was to study the role of the transient receptor potential vanilloid 1 (TRPV1), a key integrator of noxious stimuli, in the pathogenesis of pancreatic pain in a rat model of CP.MethodsCP was induced in rats by intraductal injection of trinitrobenzene sulfonic acid. TRPV1 currents in pancreas-specific DRG neurons were measured using perforated patch-clamp techniques. Reverse-transcription polymerase chain reaction was used to measure mRNA expression of TRPV1 in these neurons after laser capture microdissection. Immunofluorescence and Western blot analysis, using TRPV1-specific antibodies, also were performed. Pancreatic hyperalgesia was assessed by rat's nocifensive behavior to electrical stimulation of the pancreas.ResultsCP was associated with a 4-fold increase in capsaicin-induced current density (P < .02), along with an increase in the proportion of pancreas-specific DRG neurons that responded to capsaicin (52.9% in controls vs 79.0% in CP; P < .05). CP also was associated with a significant increase in TRPV1 expression both at the messenger RNA and protein level in whole thoracic DRGs and pancreas-specific sensory neurons. Systemic administration of the TRPV1 antagonist SB-366791 markedly reduced both visceral pain behavior and referred somatic hyperalgesia in rats with CP, but not in control animals.ConclusionsTRPV1 up-regulation and sensitization is a specific molecular mechanism contributing to hyperalgesia in CP and represents a useful target for treating pancreatic hyperalgesia caused by inflammation.

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