Abstract
Visceral afferents expressing transient receptor potential (TRP) channels TRPV1 and TRPA1 are thought to be required for neurogenic inflammation and development of inflammatory hyperalgesia. Using a mouse model of chronic pancreatitis (CP) produced by repeated episodes (twice weekly) of caerulein-induced AP (AP), we studied the involvement of these TRP channels in pancreatic inflammation and pain-related behaviors. Antagonists of the two TRP channels were administered at different times to block the neurogenic component of AP. Six bouts of AP (over 3 wks) increased pancreatic inflammation and pain-related behaviors, produced fibrosis and sprouting of pancreatic nerve fibers, and increased TRPV1 and TRPA1 gene transcripts and a nociceptive marker, pERK, in pancreas afferent somata. Treatment with TRP antagonists, when initiated before week 3, decreased pancreatic inflammation and pain-related behaviors and also blocked the development of histopathological changes in the pancreas and upregulation of TRPV1, TRPA1, and pERK in pancreatic afferents. Continued treatment with TRP antagonists blocked the development of CP and pain behaviors even when mice were challenged with seven more weeks of twice weekly caerulein. When started after week 3, however, treatment with TRP antagonists was ineffective in blocking the transition from AP to CP and the emergence of pain behaviors. These results suggest: (1) an important role for neurogenic inflammation in pancreatitis and pain-related behaviors, (2) that there is a transition from AP to CP, after which TRP channel antagonism is ineffective, and thus (3) that early intervention with TRP channel antagonists may attenuate the transition to and development of CP effectively.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Amidines / metabolism
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Analgesics, Opioid / therapeutic use
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Analysis of Variance
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Animals
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Antigens, Differentiation / metabolism
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Calcitonin Gene-Related Peptide / metabolism
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Calcium / metabolism
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Ceruletide / toxicity
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Disease Models, Animal
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Disease Progression
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Exploratory Behavior / drug effects
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Extracellular Signal-Regulated MAP Kinases / metabolism
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Ganglia, Spinal / metabolism
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Ganglia, Spinal / pathology
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Gene Expression Regulation / drug effects
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Injections, Intraperitoneal
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Male
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Mice
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Mice, Inbred C57BL
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Monocytes / metabolism
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Monocytes / pathology
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Morphine / therapeutic use
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Neutrophil Infiltration / drug effects
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Nodose Ganglion / metabolism
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Nodose Ganglion / pathology
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Oximes / therapeutic use*
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Pain / etiology
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Pain / pathology
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Pain / prevention & control*
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Pain Measurement / drug effects
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Pancreas / drug effects
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Pancreas / metabolism
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Pancreas / pathology
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Pancreatitis, Chronic / chemically induced
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Pancreatitis, Chronic / complications
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Pancreatitis, Chronic / drug therapy*
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Pancreatitis, Chronic / pathology
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Peroxidase / metabolism
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Pyridines / therapeutic use*
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RNA, Messenger / metabolism
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Sensory Receptor Cells / drug effects
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Sensory Receptor Cells / metabolism
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Sensory Receptor Cells / pathology
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TRPA1 Cation Channel
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TRPV Cation Channels / antagonists & inhibitors*
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TRPV Cation Channels / genetics
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TRPV Cation Channels / metabolism
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Time Factors
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Transient Receptor Potential Channels / antagonists & inhibitors*
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Transient Receptor Potential Channels / genetics
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Transient Receptor Potential Channels / metabolism
Substances
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A 967079
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A-889425
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Amidines
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Analgesics, Opioid
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Antigens, Differentiation
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Oximes
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Pyridines
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RNA, Messenger
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TRPA1 Cation Channel
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TRPV Cation Channels
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TRPV1 protein, mouse
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Transient Receptor Potential Channels
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Trpa1 protein, mouse
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diamidino compound 253-50
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monocyte-macrophage differentiation antigen
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Morphine
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Ceruletide
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Peroxidase
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Extracellular Signal-Regulated MAP Kinases
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Calcitonin Gene-Related Peptide
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Calcium