Hoogerwerf WA, Shenoy M, Winston JH, Xiao SY, He Z, Pasricha PJ. Trypsin mediates nociception via the proteinase-activated receptor 2: a potentially novel role in pancreatic pain.
Gastroenterology 2004;
127:883-91. [PMID:
15362043 DOI:
10.1053/j.gastro.2004.07.002]
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Abstract
BACKGROUND & AIMS
The pathogenesis of pain in pancreatitis remains poorly understood. We hypothesized that trypsin, a key inflammatory mediator in this condition, can also activate nociceptive neurons via the proteinase-activated receptor 2.
METHODS
Double immunohistochemical staining of T8 to T12 dorsal root ganglia sections was performed with antibodies against proteinase-activated receptor 2 and vanilloid receptor 1, a marker for primary nociceptive neurons. In vivo nociceptive activity was measured by FOS immunoreactivity in thoracic spinal dorsal horn segments after intrapancreatic administration of proteinase-activated receptor 2 agonists. Pain behavior was assessed by visceromotor reflex activity in response to noxious stimulation of the pancreas with proteinase-activated receptor 2 agonists.
RESULTS
Proteinase-activated receptor 2 was expressed by virtually all nociceptive neurons in thoracic dorsal root ganglia. Intraductal trypsin, in subinflammatory concentrations, activated spinal dorsal horn neurons in a dose-dependent manner, as measured by FOS expression. Both trypsin and a proteinase-activated receptor 2-specific peptide agonist induced a behavioral pain response when infused into the pancreatic duct of awake rats. Preinfusion of the pancreatic duct with proteinase-activated receptor 2-specific activating peptide desensitized the response to trypsin.
CONCLUSIONS
Our findings suggest a novel proteinase-activated receptor 2-mediated role for trypsin in the pathogenesis of pancreatic pain and one that is independent of its inflammatory effect.
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