Interaction between highly selective mu and delta opioids in vivo at the rat spinal cord.
Possible interactions between mu- and delta-receptors in the rat spinal cord were studied using the radiant-heat-induced tail flick response and the highly selective mu- or delta-ligands: [NMePhe3,D-Pro4] morphiceptin(PL-17) and cyclic[D-Pen2,D-Pen5]enkephalin(DPDPE). Intrathecal infusions of PL-17 (0.5 microgram/hr) for 5 days caused 61- and 6-fold shifts to the right of the dose-response curves for PL-17 and DPDPE, respectively. Since PL-17 and DPDPE are highly selective agonists for mu- and delta-receptors, the partial cross-tolerance to the delta-agonist induced by PL-17 is probably not resultant from a cross-reactivity between these ligands. These data suggest that there may be an interaction between mu- and delta-receptors in the rat spinal cord.
Russell
R D
RD
Department of Anesthesiology, Duke University Medical Center, Durham, N.C. 27710.
Leslie
J B
JB
Su
Y F
YF
Watkins
W D
WD
Chang
K J
KJ
D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D004361:Drug Tolerance; D004723:Endorphins / Q000494:pharmacology*; D020881:Enkephalin, D-Penicillamine (2,5)-; D004745:Enkephalins / Q000494:pharmacology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects / Q000378:metabolism*; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D013116:Spinal Cord / Q000378:metabolism*
D000700:Analgesics; D004723:Endorphins; D004745:Enkephalins; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; C044708:morphiceptin, N-Me-Phe(3)-; D020881:Enkephalin, D-Penicillamine (2,5)-