Source: Journal of Neurochemistry (2007), 100: 736-746
Article Type: Original Contribution
Authors: F. Herrera, V. Martin, G. Garcia-Santos, J. Rodriguez-Blanco, I. Antolin, C. Rodriguez


Image taken from:
http://www.virginia.edu/insideuva/2005/11/images/Jet_Lag_Graphic.jpg

Life depends on information. Melatonin, which occurs ubiquitiously in plants and animals, has been suggested as one of the first signals appearing on earth. In vertebrates, it is mainly synthesized in the pineal gland (but also other tissues) from the neurotransmitter serotonin. Melatonin, due to its chronobiotic activity, effectively attenuates jet lag symptoms, especially with eastbound flights. Moreover, melatonin has been shown to prevent neuronal cell death both in vitro and in vivo.
The article by Herrera et al. provides further inside in the mechanism of melatonin-mediated neuroprotection. The authors suggest for melatonin a novel, direct antioxidant effect targeted to the mitochondria, the key source of potentially deleterious reactive oxygen species (ROS) in cells. The protective effects of melatonin in murine hippocampal cells, however, where detected with a melatonin concentration of 1 mM (= 1000 µM), which is in contrast not only to the low micromolar concentrations that have been reported as physiological concentrations of melatonin but also to pharmacological levels, which range between 100 nM-10 µM (Kolar et al.). Bearing in mind these facts, it is somewhat difficult to estimate whether melatonin exerts the aforementioned mode of action in vivo, too.