Immunofluorescence analysis of antisense oligodeoxynucleotide-mediated 'knock-down' of the mouse δ opioid receptor in vitro and in vivo

We have previously used antisense oligodeoxynucleotides (ODN) to the cloned δ opioid receptor (DOR) to inhibit the antinociceptive response to spinally administered δ opioid receptor selective agonists in mice. Here we have examined the effect of DOR antisense ODN treatment on the level of DOR expressed in NG 108-15 cells and the spinal cord, through immune-fluorescence microscopy, to determine the efficiency and selectivity of the antisense ODN-mediated 'knock-down' of the DOR in these tissues. Antisense ODN, but not mismatch control, treatment resulted in a significant reduction in DOR immunoreactivity (-ir) in NG 108-15 cells and spinal cord. Thus, the inhibition of antinociceptive response to intrathecal δ selective agonists by DOR antisense ODN correlates with the loss of DOR-ir in the superficial layers of the dorsal horn of the spinal cord.