Effects of interferon-alpha, interferon-gamma and cAMP on the transcriptional regulation of the serotonin transporter.

We examined the effects of interferon-alpha and -gamma, which are known to have psychiatric side effects including depression, on the transcriptional regulation of the serotonin transporter and the uptake activity of the serotonin transporter in order to clarify the involvement of the serotonin transporter in the pathogenesis of interferon-induced depression. In human placental choriocarcinoma cells (BeWo cells), both messenger RNA (mRNA) for the serotonin transporter and the imipramine-sensitive uptake of serotonin were detected. The levels of serotonin transporter mRNA were increased by treatment with interferon-alpha and -gamma for 3 h. The increase in serotonin transporter mRNA elicited by the interferons was inhibited by treatment with actinomycin D, an inhibitor of transcription. Treatment with interferon-alpha or -gamma for 3-6 h, but not for 30 min, increased the uptake activity of the serotonin transporter. Treatment with dibutyryl cAMP (Dib-cAMP) which was reported to up-regulate the transcription of the serotonin transporter, also increased the mRNA levels and the activity of serotonin transporter in BeWo cells. The levels of serotonin transporter mRNA gradually increased after treatment with Dib-cAMP over 24 h, while the maximal increase in serotonin transporter mRNA elicited by the interferons was detected 3 h after the treatment. The level of serotonin transporter mRNA was increased both in the midbrain and adrenal glands of mice which were treated with interferons for 3 h. These results suggest that the interferon-induced psychiatric side effects arise through regulation of serotonin transporter transcription and that the transcriptional regulation of the serotonin transporter is a possible neurochemical mechanism of affective disorders.