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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.