Characterization of nuclear T3 receptors in human neuroblastoma cells SH-SY5Y: Effect of differentiation with sodium butyrate and nerve growth factor

Nuclear receptors for the thyroid hormone triiodothyronine (T₃) have been identified in vivo in brain tissues and in vitro in mouse and rat neuroblastoma and glioma cells. The present study characterizes nuclear T₃ receptors in human neuroblastoma SH-SY5Y cells and compares their levels before and after differentiation. Undifferentiated cells, grown in DME/HAM F-12 medium supplemented with 10% fetal calf serum, show an abundant single type of nuclear receptor, indicated by a straight Scatchard plot, with aK_d of 0.11 nmol/l. After treatment with sodium butyrate (0.5 mM for 4 days) or NGF (2 nM for 6 days), the cells showed neuronal-like patterns (extension of neurites, slowing of growth, increased tyrosine hydroxylase activity), with a decrease in the number of nuclear T₃ receptors. As sodium butyrate and NGF treatments differentiate neuroblastoma SH-SY5Y cells, these data suggest a down-regulation of T₃ receptors with cell maturation.