ABSTRACT

Aims:

Circadian rhythm of human body is regulated by melatonin which affects through to hypothalamic area of brain. Human clock genes (Clock, Bmal1, etc.) also actively participate in the circadian rhythm. Cell viability techniques reflect the number of living cells in a population. In this manuscript, human neuroblastoma cell viability was found in melatonin usage. The clock gene expression differences on the same panel were analyzed.

Methods:

In cell viability studies, MTT and trypan blue assays were used with melatonin solutions (in 0.25mM, 0.50mM, 1mM concentrations) on neuroblastoma cells. In the expressions studies, Clock, Bmal1, Per and Cry genes were studied for gene expressions by using melatonin on RT-PCR.

Results:

The melatonin’ LD50 was found as 1.2 mM on human neuroblastoma cells. We found that, 81±1.2%, 80±0.9%, 73±1.2%, 73±1.1% cells were viable in control, 0.25mM,0.50 mM, 1mM melatonin concentrations respectively. In high melatonin concentrations (0.5mM and 1mM), Clock and Bmal1 expressions were found higher than control (p<0.05). In low melatonin concentration (0.25mM), no difference in expression was found on Clock and Bmal 1 genes (p≥0.05). No difference in expressions was found in Per and Cry genes by using melatonin (p≥0.05).

Conclusions:

Melatonin in high concentrations decreased neuroblastoma cell viability. In the same concentrations, melatonin increased the Clock and Bmal1 genes’ expressions. Melatonin in low concentration did not chanced cell viability. In the same concentration, no effect on Clock and Bmal1 genes’ expressions were observed. We observed no relationship between Per and Cry genes’ expressions and melatonin usage.