Morphine does not reduce the intraspinal release of calcitonin gene-related peptide in the cat.
In anaesthetised cats, antibody microprobes were used to measure the release of immunoreactive calcitonin gene-related peptide (irCGRP) in the lumbar dorsal horn during stimulation of non-nociceptive or nociceptive primary afferent fibres. Release of irCGRP was detected in the substantia gelatinosa, where immunostaining for CGRP was subsequently observed. Intravenous administration of morphine did not affect release of irCGRP detected during either non-nociceptive or nociceptive afferent stimulation. The results suggest that the analgesic action of morphine does not involve reduced release of CGRP from the central terminals of nociceptive primary afferents.
Morton
C R
CR
Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra.
Hutchison
W D
WD
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D002415:Cats; D004558:Electric Stimulation; D005557:Formaldehyde; D007150:Immunohistochemistry; D007457:Iodine Radioisotopes; D009020:Morphine / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D011108:Polymers; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*; D013194:Staining and Labeling
D007457:Iodine Radioisotopes; D011108:Polymers; D005557:Formaldehyde; D009020:Morphine; D015740:Calcitonin Gene-Related Peptide; C003043:paraform