title: Effects of intraperitoneal and intracerebroventricular injection of crocin on acute corneal pain in rats.
abstract: In this study, the effects of intraperitoneal (i.p.) and intracerebroventricular (i.c.v.) injection of crocin in separate and combined treatments with i.p. injections of morphine (an opioid receptor agonist) and naloxone (an opioid receptor antagonist) were investigated on acute corneal pain in rats. Acute corneal pain was induced by local application of a drop of 5 M NaCl solution on the corneal surface. The number of eye wipes was taken as a pain response, and counted during the first 30 s. Crocin injected i.p. and i.c.v. and morphine injected i.p. significantly (p < 0.05) decreased the number of eye wipes. Morphine (i.p.)-induced antinociception was significantly (p < 0.05) increased by the systemically and centrally injected crocin. The antinociceptive effects induced by i.p. and i.c.v. injections of crocin were not reversed by i.p. injection of naloxone. These findings indicated that both crocin and morphine attenuated hypertonic saline-induced corneal pain. The opioid receptors may not be involved in the analgesic mechanism of crocin.
authors.affiliation: Division of Physiology, Department of Basic Sciences, Faculty of Veterinary Medicine, PO Box 1177, Urmia University, Urmia 57135, Iran. e_tamaddonfard@yahoo.com
authors.forename: Esmaeal
authors.initials: E
authors.lastname: Tamaddonfard
authors.forename: Nasrin
authors.initials: N
authors.lastname: Hamzeh-Gooshchi
mesh_terms: D000701:Analgesics, Opioid / Q000627:therapeutic use*; D000818:Animals; D002338:Carotenoids / Q000627:therapeutic use*; D003315:Cornea / Q000187:drug effects*; D004338:Drug Combinations; D007274:Injections, Intraperitoneal; D007276:Injections, Intraventricular; D008297:Male; D009020:Morphine / Q000627:therapeutic use; D009270:Naloxone / Q000627:therapeutic use; D010146:Pain / Q000188:drug therapy*; D010147:Pain Measurement; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000701:Analgesics, Opioid; D004338:Drug Combinations; D002338:Carotenoids; D009270:Naloxone; D009020:Morphine; C029036:crocin