Role of the delta-opioid receptor in (1DMe)NPYF mediated antinociception

A selective delta -opioid antagonist, naltrindole, was used to study the ro le of the delta -opioid receptor in the antinociceptive actions of a synthe tic NPFF analog, (1DMe)NPYF. I.t. (1DMe)NPYF (5 nmol) produced antinocicept ion in the rail flick test and(1DMe)NPYF (0.5 nmol) potentiated the antinoc iceptive effect of i.t. morphine 7.8 nmol. (1DMe)NPYF (5 nmol) had an antih yperalgesic effect in carrageenan inflammation and it significantly reduced mechanical allodynia in the spinal nerve ligation model. All these effects were prevented or significantly reduced by protreatment with naltrindole ( 28 nmol) (P < 0.01-0.001). These data suggest that activation of spinal <de lta>-opioid receptors plays an important rule in mediating the spinal antin ociceptive effects of (1DMe)NPYF. (C) 2001 Elsevier Science Inc. All rights reserved.