The effects of nitrous oxide on the central endogenous pro-opiomelanocortin system in the rat.
The hypothesis that nitrous oxide stimulates the central pro-opiomelanocortin system in vivo was explored in this study. A concentration-dependent stimulation of central pro-opiomelanocortin neuropeptides was demonstrated after exposures to variable concentrations of nitrous oxide with oxygen. Rats exposed to 60% and 80% nitrous oxide with oxygen demonstrated an elevation of beta-endorphin concentration along the neuraxis involved with analgesia; no similar effect was observed in alpha-MSH concentration, neither duration of exposure nor acclimation to the enclosed environment altered this stimulation. The discontinuation of nitrous oxide exposure resulted in the diminution of beta-endorphin concentration to pre-exposure levels in 15-30 min. With an ACTH1-39 antisera, a semiquantitative increase in opiocortin immunoreactivity after exposures to nitrous oxide was demonstrated. In conclusion, the increase in beta-endorphin concentration and immunoreactive ACTH1-39 staining in the cells of origin, areas of fiber projection and terminal fields suggest that nitrous oxide stimulates the central pro-opiomelanocortin system in vivo in the rat.
Zuniga
J R
JR
Neuroendocrine Unit, University of Rochester, NY 14642.
Joseph
S A
SA
Knigge
K M
KM
D000280:Administration, Inhalation; D000818:Animals; D001933:Brain Stem / Q000187:drug effects / Q000378:metabolism*; D005625:Frontal Lobe / Q000187:drug effects / Q000378:metabolism*; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009609:Nitrous Oxide / Q000494:pharmacology*; D011333:Pro-Opiomelanocortin / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D000521:alpha-MSH / Q000378:metabolism; D001615:beta-Endorphin / Q000378:metabolism
D011498:Protein Precursors; D000521:alpha-MSH; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; D009609:Nitrous Oxide