Regulation of delta opioid receptor expression by anti-CD3-epsilon, PMA, and ionomycin in murine splenocytes and T cells.

Previous studies have shown that low levels of delta opioid receptor (DOR) mRNA were detectable by reverse transcription polymerase chain reaction (RT-PCR) in unstimulated splenocytes from BALB/c female mice. This study demonstrates that DOR transcripts can be detected in freshly obtained splenocytes froin CD 1 female mice as well. The results of studies using quantitative competitive RT-PCR showed that DOR transcripts in splenic T cells increased from < 1 copy/cell to 22 and 42 copies/cell, respectively, after stimulation with anti-CD3-epsilon for 24 and 48 h compared to the level in freshly obtained T cells. In the presence of actinomycin D, anti-CD3-epsilon did not affect the rate of degradation of DOR mRNA, suggesting that its stability is not altered by anti-CD3-epsilon. After incubation with phorbol myristate acetate (PMA) and ionomycin, the expression of DOR mRNA in splenocytes and T cells was significantly reduced compared with unstimulated cells in culture. In addition, the inhibitory effect of PMA prevented anti-CD3-epsilon-stimulated DOR expression. These data suggest that signaling through the T cell receptor complex by anti-CD3-epsilon regulates DOR expression differently than PMA and ionomycin.