Retinoic acid downregulates the expression of ciliary neurotrophic factor in rat Schwann cells.

Neuropoietic cytokines, which serve as mediators in neuroglial interactions, are differentially regulated after peripheral nerve injury. In Schwann cells, the expression of ciliary neurotrophic factor (CNTF) decreases. Pursuing the hypothesis that retinoic acid (RA) serves as a regulator of lesion-induced cytokine signaling we found that all RA receptors and retinoid X receptors are expressed in Schwann cell primary cultures. Using quantitative reverse transcription-polymerase chain reaction, we have investigated the effect of RA on the expression of CNTF in these cells. After treatment with 10 nM all-trans RA for 22 h the concentration of CNTF mRNA was reduced to 63% of the control level, reminiscent of the regulation after nerve injury in vivo. In addition to CNTF, the mRNAs of leukemia inhibitory factor, interleukin-6, ciliary neurotrophic factor receptor component alpha and gp130 were detected in the Schwann cells.