Fig. 5.

mRNA expression of P2X₇ nucleotide receptors is not regulated by retinoic acid treatment. Human SH-SY5Y neuroblastoma cells were grown to 80% confluency onto cell culture Petri dishes in normal serum. Then, cells were subjected to medium replacement containing N: normal serum or L: low serum. Both cultures were supplemented with 15 μM RA as described in “Materials and methods” section. Chronic RA treatment was performed by replacing the corresponding medium with fresh medium supplemented with 15 μM RA every 2 days. On the experimental day 5, mRNA levels of P2X₇ nucleotide receptors were determined by semi-quantitative RT–PCR analysis as described in “Materials and methods” section. P2X₇ nucleotide receptors mRNA expression was normalized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Non-RA treated cells (undifferentiated cells) served as controls. For reference, the first bar on graph and lane 2 on gel represent P2X₇ nucleotide receptors mRNA expression at the experimental day 0 (control). Data are the means ± SEM of values of four independent experiments. Representative gels are shown