1,4-Benzodiazepines Antagonize Opiate-Induced Antinociception in Mice

Abstract
Th tests of nociception. Flunitrazepam antagonized the antinociceptive effect only in the tail-flick test. The benzodiazepine effect could not be explained by altered tail-skin temperature. The antagonism did not correlate well with the sedative or muscle-relaxing properties of the benzodiazepines, and a different mechanism may therefore be involved. It is proposed that the antagonism represents an interaction between benzodiazepines and opioid systems in the brain participating in modulation of nociceptive inputs. Address correspondence to Dr. Rosland, Department of Physiology, University of Bergen, Årstadveien 19, N-5009 Bergen, Norway. J. H. Rosland is a Fellow of the Norwegian Cancer Society— Den norske kreftforening. Accepted for publication May 11, 1990. © 1990 International Anesthesia Research Society...