Effects of systemic morphine upon A delta- and C-fibre evoked activities of subnucleus reticularis dorsalis neurones in the rat medulla.
The effects of intravenous administration of morphine were examined on A delta- and C-fibre evoked activities of subnucleus reticularis dorsalis (SRD) neurones in the rat medulla. This region may have an important role in nociception since SRD neurones exhibit whole body receptive fields from which they can be activated preferentially or exclusively by noxious stimulation. The present study demonstrates that morphine can depress the C-fibre evoked responses of SRD neurones in a dose-related (3-12 mg/kg range) and naloxone reversible fashion; however the A delta-fibre evoked responses of these neurones were depressed only with the greatest dose employed. Since a similar dose can depress by 50% the C-fibre evoked activities of SRD and spinal dorsal horn convergent neurones, it is suggested that the depressant effect of morphine on SRD neurones arises primarily from its spinal action.
Bing
Z
Z
Unité de Recherches de Neurophysiologie Pharmacologique de l'INSERM (U. 161), Paris, France.
Villanueva
L
L
Le Bars
D
D
D000818:Animals; D004558:Electric Stimulation; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000502:physiology*; D009020:Morphine / Q000494:pharmacology*; D009412:Nerve Fibers / Q000187:drug effects* / Q000502:physiology; D009413:Nerve Fibers, Myelinated / Q000187:drug effects* / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains
D009020:Morphine