Bonaz, Rivière, Sinniger
Apr 1, 2000
Citations
3
Influential Citations
42
Citations
Journal
Neurogastroenterology & Motility
Abstract
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 κ‐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.