The expression of MTNR3 and nuclear receptors in murine leucocytes.

AIM The aim of this study was to investigate the expression of melatonin receptor MTNR3 and nuclear receptors in murine lymphocytes and their dependence on lighting conditions and circadian time. MATERIALS AND METHODS The mRNA levels of melatonin receptors were investigated in cells isolated from thymus, spleen, lymph nodes and bone marrow during the day or during the night. RESULTS The expression of MTNR3 in B-cells and bone marrow cells was much higher than in thymocytes and T-cells. Retinoic acid receptor-related orphan receptor A (Rora) was found mostly in thymocytes and cluster of differentiation 4 positive (Cd4(+)) T cells. Rorc was detected in thymocytes; its expression in peripheral T-cells was very low. Rorb was not detected in lymphocytes. MTNR3 transcripts in B-cells and Rorc transcripts in thymocytes increased during the day and decreased during the night. CONCLUSION Circadian time and lighting could be involved in the regulation of the expression of melatonin receptors MTNR3 and Rorc.