title: Effects of subcutaneous and intracerebroventricular injection of physostigmine on the acute corneal nociception in rats.
abstract: The present study investigated the effects of subcutaneous (sc) and intracerebroventricular (icv) injections of physostigmine (a cholinesterase inhibitor), atropine (an antagonist of muscarinic cholinergic receptors) and hexamethonium (an antagonist of nicotinic cholinergic receptors) on the acute corneal nociception in rats. Local application of 5 M NaCl solution on the corneal surface of the eye produced a significant nociceptive behavior, characterized by eye wiping. The number of eye wipes was counted during the first 30 s. The sc (0.25, 0.5 and 1 mg/kg) and icv (1.25, 2.5, 5 and 10 μg) injections of physostigmine significantly (p < 0.05) decreased the number of eye wipes. Atropine and hexamethonium at (2 mg/kg, sc and 20 μg, icv) had no effects when used alone, however, atropine, but not hexamethonium prevented the antinociception induced by physostigmine (sc and icv). The results of this study indicate that the central muscarinic, but not nicotinic receptors might be involved in the antinociceptive effect of physostigmine in the acute corneal model of pain in rats.
authors.affiliation: Division of Physiology, Department of Basic Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia 57153-1177, 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: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002800:Cholinesterase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use*; D003315:Cornea / Q000187:drug effects* / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D018738:Hexamethonium / Q000494:pharmacology; D007276:Injections, Intraventricular; D007279:Injections, Subcutaneous; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D010146:Pain / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D010147:Pain Measurement; D010830:Physostigmine / Q000494:pharmacology* / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D012965:Sodium Chloride
chemical_list: D002800:Cholinesterase Inhibitors; D018727:Muscarinic Antagonists; D018733:Nicotinic Antagonists; D018738:Hexamethonium; D012965:Sodium Chloride; D001285:Atropine; D010830:Physostigmine