Opioid-induced stimulation of fetal respiratory activity by [D-Ala2]deltorphin I.
[D-Ala2]deltorphin I effects on fetal respiratory activity was characterized to determine the role delta-opioid receptors play in modulating fetal respiratory activity. [D-Ala2]deltorphin I, infused at 0.3 or 100 micrograms/h, intracerebroventricularly (i.c.v.), stimulated fetal respiratory activity without changing blood pH, PCO2 or PO2. Stimulation by 0.3 micrograms/h, but not 100 micrograms/h, was blocked by i.c.v. infusion of the delta-opioid receptor antagonist, naltrindole. Stimulation by 100 micrograms/h was blocked by the mu 1-opioid receptor antagonist naloxonazine. These data suggest stimulation of fetal respiratory activity by 0.3 micrograms/h [D-Ala2]deltorphin I are mediated specifically through delta-opioid receptors; while [D-Ala2]deltorphin I at 100 micrograms/h is no longer selective for the delta-opioid receptor, and the stimulation may be mediated through the mu 1-opioid receptor.
Cheng
P Y
PY
Department of Pharmacology, Cornell University Medical College, New York, NY 10021.
Wu
D
D
Decena
J
J
Soong
Y
Y
McCabe
S
S
Szeto
H H
HH
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004576:Electromyography; D005260:Female; D005333:Fetus / Q000502:physiology*; D007211:Indoles / Q000494:pharmacology; D007276:Injections, Intraventricular; D009019:Morphinans / Q000494:pharmacology; D009270:Naloxone / Q000031:analogs & derivatives / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives*; D009292:Narcotic Antagonists / Q000494:pharmacology; D009842:Oligopeptides / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D011247:Pregnancy; D017465:Receptors, Opioid, delta / Q000187:drug effects; D012119:Respiration / Q000187:drug effects*; D012756:Sheep
D007211:Indoles; D009019:Morphinans; D009292:Narcotic Antagonists; D009842:Oligopeptides; D017465:Receptors, Opioid, delta; C060209:deltorphin II, Ala(2)-; D009270:Naloxone; D009271:Naltrexone; C034643:naloxonazine; C055382:naltrindole