Cc. Chien et Gw. Pasternak, (-)-PENTAZOCINE ANALGESIA IN MICE - INTERACTIONS WITH A SIGMA-RECEPTOR SYSTEM, European journal of pharmacology, 294(1), 1995, pp. 303-308
(-)-Pentazocine is active in the tailflick assay in CD-1 mice, althoug
h it shows a biphasic dose-response curve with a peak effect of only 3
0%. Co-administration of haloperidol shifts the dose-response curve to
the left and elevates the maximal response to 70% through a blockade
of sigma(1) receptors, but the curve remains biphasic. (+)-Pentazocine
is inactive in all antinociceptive assays, either alone or with halop
eridol. The analgesic actions of (-)-pentazocine are readily reversed
by nor-binaltorphimine, but not by the mu-selective opioid receptor an
tagonist beta-funaltrexamine, implying a kappa(1)-opioid receptor mech
anism of action. This conclusion is supported by the ability of antise
nse oligodeoxynucleotides directed against the KOR-1 clone, which enco
des the kappa(1)-opioid receptor, to block(-)-pentazocine analgesia.