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 frost BALB/c female mice, This study demo nstrates that DOR transcripts can he detected in freshly obtained splenocyt es from CD1 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 stimulatio n with anti-CD3-epsilon for 24 and 48 h compared to the level in freshly ob tained T cells. Ill 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 cult ure, In addition, the inhibitory effect of PMA prevented anti-CD3-epsilon-s timulated DOR expression. These data suggest that signaling through the T c ell receptor complex by anti-CD3-epsilon regulates DOR expression different ly than PMA and ionomycin..