Effect of granulocyte-macrophage colony stimulating factor and granulocyte colony stimulating factor on prolactin and adrenocorticotropic hormone secretion in rats: dose- and time-response in vivo studies.

The in vivo effect of granulocyte-macrophage colony stimulating factor (GM-CSF) and granulocyte colony stimulating factor (G-CSF) on the plasma levels of prolactin (PRL) and adrenocorticotropic hormone (ACTH) in rats were studied. The administration of 10 micrograms/kg G-CSF at 45 min (p < 0.05) and 90 min (p < 0.01) or 10 micrograms/kg GM-CSF at 45 and 90 min (p < 0.01) stimulated the secretion of ACTH. Moreover, G-CSF administration only, in doses of 10 micrograms/kg at 45 min (p < 0.05) and 90 min (p < 0.01) augmented PRL secretion into the blood. These experiments suggest that the human colony stimulating factors (GM-CSF and G-CSF) activate the anterior pituitary gland in vivo to ACTH secretion, but only G-CSF positively influenced PRL release in rats.