fedotozine and Intestinal-Obstruction

Fedotozine, a kappa opioid agonist, reverses digestive ileus caused by acetic acid (AA)-induced visceral pain in rats. The aims of this study were: to map, in conscious rats, central pathways activated by AA using Fos as a marker of neuronal activation; to characterize primary afferent fibres involved in this activation; and to investigate the effect of fedotozine on AA-induced Fos expression. AA (0.6%; 10 mL kg-1) was injected i.p. in conscious rats either untreated; pretreated 14 days before with capsaicin; pretreated 20 min previously with fedotozine; or pretreated 2 h prior to fedotozine with the kappa-antagonist nor-binaltorphimine (nor-BNI). Controls received the vehicle alone. 60 min after injection of AA, rats were processed for Fos immunohistochemistry. Visceral pain was assessed by counting abdominal cramps. AA induced Fos in the thoraco-lumbar spinal cord (laminae I, V, VII and X) and numerous brain structures such as the nucleus tractus solitarius, and paraventricular nucleus (PVN) of the hypothalamus, whereas almost no Fos labelling was observed in controls. Capsaicin pretreatment blocked AA-induced Fos in all structures tested. Fedotozine significantly decreased AA-induced abdominal cramps and Fos immunoreactivity in the spinal cord and PVN, this effect being reversed by nor-BNI pretreatment. AA induces Fos in the spinal cord and numerous brain nucuei, some of which are involved in the control of digestive motility in rats. This effect is mediated through capsaicin-sensitive afferent fibres and prevented by fedotozine most likely through a peripheral action on visceral afferents.

Topics: Abdominal Pain; Acetic Acid; Afferent Pathways; Animals; Benzyl Compounds; Brain; Capsaicin; Gene Expression Regulation; Genes, fos; Injections, Intraperitoneal; Intestinal Obstruction; Male; Naltrexone; Paraventricular Hypothalamic Nucleus; Propylamines; Proto-Oncogene Proteins c-fos; Rats; Rats, Sprague-Dawley; Receptors, Opioid, kappa; Solitary Nucleus; Spinal Cord; Supraoptic Nucleus

In a rat model of postoperative ileus, induced by abdominal surgery, we investigated the effect of mu- and kappa-opioid receptors. Different degrees of inhibition of the gastrointestinal transit, measured by the migration of Evans blue, were achieved by skin incision, laparotomy or laparotomy plus manipulation of the gut. Morphine (1 mg/kg), a preferential mu-opioid receptor agonist, significantly inhibited the transit after skin incision, while the transit after the laparotomy with or without manipulation was not significantly affected. Fedotozine (5 mg/kg), a peripheral kappa-opioid receptor agonist, enhanced the transit after laparotomy plus manipulation, while naloxone (1 mg/kg), a non-specific opioid receptor antagonist, further inhibited the transit after laparotomy plus manipulation. Naloxone and fedotozine alone had no effect on the transit after skin incision or laparotomy without manipulation. However, naloxone prevented the effect of morphine on the transit after skin incision and of fedotozine on the laparotomy plus manipulation. These results support a role for peripheral kappa-opioid receptors in the pathogenesis of postoperative ileus induced by abdominal surgery.

Topics: Abdomen; Analgesics, Opioid; Animals; Benzyl Compounds; Coloring Agents; Evans Blue; Gastrointestinal Transit; Intestinal Obstruction; Male; Morphine; Naloxone; Narcotic Antagonists; Postoperative Complications; Propylamines; Rats; Rats, Wistar; Receptors, Opioid, kappa; Receptors, Opioid, mu

Two kappa agonists, fedotozine and trans-(+/-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolydinyl)-cyclohexyl ]- benzeneacetamide methanesulfonate [(+/-)U-50,488H] were used to reverse the gastrointestinal transit inhibition induced by either peritoneal irritation (PI) or intracisternal (i.c.) administration of corticotropin releasing factor (CRF). PI was induced by acetic acid given i.p. Gastric emptying and intestinal transit were estimated with a 51Cr-labeled test meal. PI inhibited both gastric emptying (-50.9%) and intestinal transit (-48.8%). These inhibitions were prevented in a dose-dependent manner by the CRF antagonist, alpha-helical-CRF9-41 at doses (1-10 nmol/rat i.c.) that had no effect in control animals. CRF (300 pmol/rat i.c.) reproduced the gastrointestinal transit inhibitions seen under PI. The CRF effects were blocked by alpha-helical-CRF9-41 (10 nmol/rat) given i.c. but not i.v. Fedotozine (1-10 mg/kg s.c. but not 300 micrograms/rat i.c.v. or intrathecally) and (+/-)U-50,488H (0.3-3 mg/kg s.c. but not 100 micrograms/kg i.c.v.) reversed PI- but not CRF-induced ileus. Neither PI-induced ileus nor the fedotozine response was affected by perivagal capsaicin treatment. It was concluded that the PI-induced ileus depends on central CRF receptors. This result is consistent with the activation of an extrinsic inhibitory reflex. The reversal by kappa agonists of PI- but not CRF-induced ileus suggests that kappa agonists do not act after but before the CRF receptors. A possible peripheral action on nonvagal sensory afferents is suggested.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Acetates; Acetic Acid; Animals; Benzyl Compounds; Capsaicin; Corticotropin-Releasing Hormone; Gastric Emptying; Gastrointestinal Motility; Intestinal Obstruction; Male; Neurons, Afferent; Peptide Fragments; Peritoneal Cavity; Propylamines; Pyrrolidines; Rats; Rats, Sprague-Dawley; Receptors, Corticotropin-Releasing Hormone

Fedotozine is a peripheral opioid agonist. Its effects were assessed in experimental ileus in rats.. Ileus was induced by abdominal surgery (laparotomy and cecum palpation) or peritonitis (acetic acid, intraperitoneally). Digestive motility was recorded by electromyography and gastrointestinal transit estimated using a 51Cr-labeled test meal.. Surgery or peritonitis inhibited motility and migrating myoelectrical complexes for 2-3 hours. In both models, fedotozine (3 mg/kg, intravenously; 10 mg/kg, subcutaneously) restored a normal motility pattern. This action was reproduced by the kappa-agonist, U-50, and 488H and was blocked by subcutaneous naloxone, naloxone-methiodide, or nor-binaltorphimine, a selective kappa-antagonist. Peritonitis induced a 57% inhibition of gastric emptying and intestinal transit that was reversed by fedotozine (1-10 mg/kg, subcutaneously) or kappa-agonists (U-50, 488H, bremazocine) but not delta-agonists (DPDPE, [D-Ala2]-deltorphin-II), whereas mu-agonists (morphine, fentanyl) potentiated ileus. Fedotozine restoration of transit was blocked by subcutaneous naloxone, naloxone-methiodide, or norbinaltorphimine but not by intracerebroventricular naloxone. Fedotozine was inactive up to 300 micrograms/rat when given intracerebroventrically or intrathecally.. Fedotozine reverses experimental ileus via an action at peripheral kappa-opioid receptors.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Abdomen; Animals; Benzyl Compounds; Gastric Emptying; Gastrointestinal Motility; Intestinal Obstruction; Male; Naloxone; Peritonitis; Propylamines; Pyrrolidines; Rats; Rats, Sprague-Dawley; Receptors, Opioid, kappa