Peripheral mechanisms of intestinal dysmotility in the morphine tolerant and dependent rats

Changes of intestinal motility and transit produced by tolerance to and dependence upon morphine have been partly attributed to peripheral mechanisms. We evaluated the effect of chronic peripheral morphine administration and peripheral mu-receptor blockade on vagal afferent activity (VAA) and c-Kit...

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Bibliographic Details
Published in:Journal of physiology and pharmacology : an official journal of the Polish Physiological Society 2006-03, Vol.57 (1), p.73
Main Authors: Banach, T, Zurowski, D, Gil, K, Weisbrodt, N W, Rosenfeld, G, Thor, P J
Format: Article
Language:English
Subjects:
Animals
Colon - drug effects
Colon - metabolism
Drug Tolerance - physiology
Duodenum - drug effects
Duodenum - metabolism
Gastrointestinal Motility - drug effects
Male
Morphine - administration & dosage
Morphine - toxicity
Morphine Dependence - physiopathology
Neurons, Afferent - drug effects
Neurons, Afferent - physiology
Proto-Oncogene Proteins c-kit - analysis
Proto-Oncogene Proteins c-kit - metabolism
Rats
Rats, Wistar
Receptors, Opioid, mu - antagonists & inhibitors
Receptors, Opioid, mu - drug effects
Receptors, Opioid, mu - metabolism
Somatostatin - analogs & derivatives
Somatostatin - pharmacology
Vagus Nerve - drug effects
Vagus Nerve - physiology
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Summary:Changes of intestinal motility and transit produced by tolerance to and dependence upon morphine have been partly attributed to peripheral mechanisms. We evaluated the effect of chronic peripheral morphine administration and peripheral mu-receptor blockade on vagal afferent activity (VAA) and c-Kit positive intramuscular cells of Cajal (ICCs). Ten rats were subjected to chronic subcutaneous morphine infusion for 72 h with subsequent VAA recording. Potential frequency was evaluated within recordings before and after mu receptor blockade by (D)-Phe -Cys -Tyr -(D)-Trp -Orn -Thr -Phe -Thr (CTOP) i.p. injections. Afterwards the rats were sacrificed and intramuscular c-Kit antigen expression was assessed by image analysis within removed fragments of duodenum and ascending colon. An equal group of rats served as a control for VAA and c-Kit expression. Analysis of VAA revealed similar frequencies of potentials in morphine tolerant / dependent rats before CTOP and in the controls. CTOP increased potential frequency in the morphine group which effect was visible mostly within the first 20 minutes (p=0.01). The morphine infused animals presented also higher c-Kit expression in both the duodenum (p
ISSN:0867-5910