Oxytocin blocks the development of heroin-enkephalin cross-tolerance in mice.
The development of cross-tolerance to an analgesic effect has been observed between a mu-receptor agonist, heroin, and a delta-receptor agonist, Met2-Pro5-enkephalinamide. Repeated treatments with heroin twice a day for 4 days resulted in a decreased nociceptive effect to enkephalin on day 5. The enkephalin dose-response line was shifted to the right, considered a sign of the development of cross-tolerance. Peripheral treatment with oxytocin blocked the development of heroin-enkephalin cross-tolerance. A similar effect was observed after intracerebroventricular administration of oxytocin, supporting our assumption that oxytocin blocks the development of heroin-enkephalin cross-tolerance via CNS mechanisms.
Kriván
M
M
Department of Pathophysiology, Albert Szent-Györgyi Medical University, Szeged, Hungary.
Szabó
G
G
Sarnyai
Z
Z
Kovács
G L
GL
Telegdy
G
G
D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives / Q000494:pharmacology; D004745:Enkephalins / Q000494:pharmacology*; D003932:Heroin / Q000494:pharmacology*; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009619:Nociceptors / Q000187:drug effects; D010121:Oxytocin / Q000494:pharmacology*; D010147:Pain Measurement / Q000187:drug effects; D011930:Reaction Time / Q000187:drug effects
D000700:Analgesics; D004745:Enkephalins; D010121:Oxytocin; D004744:Enkephalin, Methionine; C021717:enkephalin, Met(2)-ProNH2(5)-; D003932:Heroin