Differential antagonism by MK-801 against antinociception induced by opioid receptor agonists administered supraspinally in mice.
Various doses of MK-801 ((+/-)-5-methyl-10,11-dihydro-5H-dibenzo(a,d) cyclohepten-5, 10-imine maleate), a non-competitive N-methyl-D-aspartic acid (NMDA) receptor antagonist (0.001-1 microgram) injected intracerebroventricularly (i.c.v.) alone did not show any antinociceptive effect. MK-801 (0.001-1 microgram i.c.v.) dose dependently attenuated the inhibition of the tail-flick and hot plate responses induced by i.c.v. administered morphine (1 microgram), [D-Pen2, D-Pen5]enkephalin (DPDPE; 10 micrograms), and U50,488H (trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeoce tamide ) 60 micrograms). However, the inhibition of the tail-flick and hot plate responses induced by i.c.v. administered beta-endorphin (1 microgram) was not changed by i.c.v. administered MK-801. Our results indicate that, at the supraspinal level, NMDA receptors are involved in the production of antinociception induced by supraspinally administered morphine, DPDPE, and U50,488H but not beta-endorphin.
Suh
H W
HW
Department of Pharmacology, College of Medicine, Hallym University, Kangwon-Do, South Korea.
Song
D K
DK
Kim
Y H
YH
Yoo
J S
JS
Tseng
L F
LF
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000700:Analgesics / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D020881:Enkephalin, D-Penicillamine (2,5)-; D004745:Enkephalins / Q000037:antagonists & inhibitors; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine / Q000037:antagonists & inhibitors; D011759:Pyrrolidines / Q000037:antagonists & inhibitors; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects; D011957:Receptors, Opioid / Q000819:agonists*; D001615:beta-Endorphin / Q000037:antagonists & inhibitors
D000700:Analgesics; D004745:Enkephalins; D011759:Pyrrolidines; D016194:Receptors, N-Methyl-D-Aspartate; D011957:Receptors, Opioid; D001615:beta-Endorphin; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D016291:Dizocilpine Maleate; D009020:Morphine; D020881:Enkephalin, D-Penicillamine (2,5)-