Induction of GDNF mRNA expression by melatonin in rat C6 glioma cells.

In order to determine the physiological effect of melatonin on glial cell line-derived neurotrophic factor (GDNF), which is reportedly up-regulated by high doses of this hormone, concentration-dependent studies were carried out in cultured cells. RT-PCR studies indicated that, in addition to GDNF, rat C6 glioma cells express both of the G protein-coupled melatonin receptor subtypes, MT1 and MT2. When C6 cells were treated with physiological (0.05-1 nM) or higher (10 and 100 nM) concentrations of melatonin for 24 h, a significant induction of relative GDNF mRNA levels (n = 4) was detected by semi-quantitative RT-PCR. These findings suggest that induction of GDNF is involved in physiological neuroprotection by melatonin. Given the potency of GDNF in maintaining nigrostriatal dopaminergic integrity, understanding the mechanisms of its induction by melatonin could provide novel therapies for Parkinson's disease.