The Effects of the Neurohormone Melatonin on Avian Macrophage Cell Function
McKenna, Sarah J.
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Within the past year the neurohormone melatonin has been popularized as the newest wonder drug. Claims of its miracles range from better sleep at night to enhancing the immune system. Melatonin has been shown to activate macrophage cells, which certainly could enhance immune function. The purpose of this experiment was two fold. First, a cytotoxicity study was conducted to determine if the concentrations of melatonin tested were toxic to the avian macrophage cell line, MQ-NCSU. Secondly, a phagocytosis assay was conducted to determine how well these macrophage cells phagocytose either sheep red blood cells (SRBC) or Escherichia coli (E. coli) after being exposed to melatonin. The concentrations of melatonin tested were 250,100, 50, and 10 picograms/mL, which are representative of biological levels. None of the concentrations of melatonin tested were shown to be toxic. The results of the phagocytosis assays also were negative. Melatonin was not shown to enhance the ability of MQ-NCSU macrophage cells to phagocytose either SRBC or E. coli. Although these results do not support the claim that melatonin itself directly enhances this portion of the immune system, these results can be explained by the theory that melatonin acts indirectly through a system of cell-derived opioid peptides. If other chemical mediators are necessary to produce immunoenhancement, melatonin would be expected to be ineffective in an in vitro study such as this one.