Effect of naloxone on tooth pulp-evoked jaw-opening reflex in the barbiturate-anaesthetized cat.
The threshold of the tooth pulp-evoked jaw-opening reflex was uninfluenced by administration of 0.5 or 5.0 mg kg-1, i.v. naloxone, a specific opioid antagonist, in the barbiturate-anaesthetized cat. Furthermore, facilitatory or inhibitory interactions between two successive tooth pulp-evoked jaw reflex responses were not influenced by naloxone. It is concluded that naloxone-sensitive opioid receptor-mediated mechanisms do not contribute to the modulation of tooth pulp-evoked reflexes by conditioning dental stimuli. Also they do not exert a tonic inhibition on the sensory or motor part of the tooth pulp-driven reflexes. Experiments performed for comparison showed that the non-nociceptive polysynaptic reflex discharge in the flexo-motor neurons of the limb was not influenced by naloxone either.
Huopaniemi
T
T
Department of Physiology, University of Helsinki, Finland.
Pertovaara
A
A
Jyväsjärvi
E
E
Carlson
S
S
D000818:Animals; D002415:Cats; D003782:Dental Pulp / Q000187:drug effects*; D007568:Jaw / Q000187:drug effects*; D008465:Mechanoreceptors / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects; D017981:Receptors, Neurotransmitter / Q000187:drug effects; D012018:Reflex / Q000502:physiology*; D013270:Stomach / Q000187:drug effects
D017981:Receptors, Neurotransmitter; D009270:Naloxone