Effect of granulocyte-macrophage colony stimulating factor and granulocyte colony stimulating factor on melatonin secretion in rats in vivo and in vitro studies.

The study was performed in order to clarify whether granulocyte-macrophage colony stimulating factor (GM-CSF) and granulocyte colony stimulating factor (G-CSF) affect melatonin production and release. We have found that both factors (GM-CSF at doses of 10.0 and 100.0 micrograms/kg, and G-CSF at doses of 1.0, 10.0, and 100.0 micrograms/kg) stimulate melatonin secretion in rats in vivo. Positive correlations between tested doses of GM-CSF and G-CSF and plasma melatonin levels were observed (P < 0.01). Moreover, GM-CSF at doses of 2.0 and 20.0 ng/ml activated in vitro the pineal gland to melatonin release (P < 0.05) in a dose-dependent manner.