ANTISENSE OLIGODEOXYNUCLEOTIDE TO A DELTA-OPIOID RECEPTOR GIVEN INTRATHECALLY BLOCKS ICV ADMINISTERED BETA-ENDORPHIN-INDUCED ANTICIPATION IN THE MOUSE

The antinociception induced by supraspinally administered beta-endorphin is mediated by the release of Met-enkephalin and subsequent stimulation of delta-opioid receptors from the spinal cord in mice. Repeated intrathecal administration of an antisense oligodeoxynucleotide against delta-opioid receptors selectively attenuated i.c.v. administered beta-endorphin induced antinociception without any effect on the antinociception induced by mu-opioid receptor agonists, morphine and DAMGO, or kappa-opioid receptor agonists, U50,488H. A random sequence oligodeoxynucleotide was inactive against beta-endorphin-induced antinociception. The study confirms previous findings that the antinociception induced by beta-endorphin is mediated by the stimulation of the delta-opioid receptors in the spinal cord.