To determine whether this inhibitory effect of melatonin over aromatase activity was due to a downregulation of the aromatase expression at the transcriptional level, we then incubated glioma cells with either melatonin (1 mM, 1 μM or 1 nM) or vehicle for 90 min and total RNA was isolated to perform real-time PCRs with specific primers for rat aromatase. The gene discussed is CYP19A1; the disease is central nervous system cancer.