title: Evaluation of the antinociceptive activities of enaminone compounds on the formalin and hot plate tests in mice.
abstract: Recently, we found that methyl 4-(4'-bromophenyl)aminocyclohex-3-en-6-methyl-2-oxo-1-oate (E139), an anticonvulsant enaminone, has antinociceptive activity in the hot plate test. In this study we evaluated the antinociceptive activity of five anilino enaminones E139, ethyl 4-(4'-chlorophenyl)amino-6-methyl-2-oxocyclohex-3-en-1-oate (E121), ethyl 4-(4'-bromophenyl)amino-6-methyl-2-oxocyclohex-3-en-1-oate (E122), methyl 4-(4'-chlorophenyl)amino-6-methyl-2-oxocyclohex-3-en-1-oate (E138) and ethyl 4-(4'-fluorophenyl)amino-6-methyl-2-oxocyclohex-3-en-1-oate (BRG 19) using the formalin and hot plate tests. E139 has been reported to exert its effects via enhancement of extracellular GABA levels, thus tiagabine, a GABA transporter inhibitor, was evaluated as a control together with indomethacin. Tiagabine had antinociceptive activity in both phase 1 (neurogenic pain) and phase 2 (inflammatory pain) of the formalin test, whereas indomethacin had activity only in phase 2. E139 and E138 had antinociceptive activity in both phases of the formalin test, whereas E121 had activity only in phase 1 and BRG 19 had activity only in phase 2. E122 had no significant activity in either phase. In the hot plate test only E139 had antinociceptive activity. Administration of either bicuculline, a GABAA receptor antagonist, or CGP 35348, a GABAB receptor antagonist, blocked the antinociceptive activity of E139. In conclusion our results indicate that E139 has antinociceptive activity in the formalin and hot plate tests that are dependent on GABA receptors.
authors.affiliation: Department of Pharmacology and Therapeutics, Faculty of Pharmacy, Kuwait University, Kuwait.
authors.forename: Willias
authors.initials: W
authors.lastname: Masocha
authors.affiliation: Department of Pharmacology and Therapeutics, Faculty of Pharmacy, Kuwait University, Kuwait.
authors.forename: Samuel B
authors.initials: SB
authors.lastname: Kombian
authors.affiliation: Department of Pharmaceutical Sciences, School of Pharmacy, University of Saint Joseph, Hartford, CT 06103, USA.
authors.forename: Ivan O
authors.initials: IO
authors.lastname: Edafiogho
mesh_terms: D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D003510:Cyclohexanes / Q000494:pharmacology*; D005260:Female; D018756:GABA Antagonists; D051379:Mice; D010146:Pain / Q000188:drug therapy*
chemical_list: D000700:Analgesics; D003510:Cyclohexanes; C482385:E139 compound; D018756:GABA Antagonists