Scientists at Emory University School of Medicine have discovered unexpected properties for a precursor to melatonin, the hormone that regulates sleep cycles.
Melatonin is produced from the neurotransmitter serotonin in a daily rhythm that peaks at night. Melatonin's immediate precursor, N-acetylserotonin, was not previously thought to have effects separate from those of melatonin or serotonin.
Now an Emory team has shown that N-acetylserotonin can stimulate the same circuits in the brain activated by the growth factor BDNF (brain-derived neurotrophic factor).
The results will be published online this week in the Proceedings of the National Academy of Sciences.
The team was led by Keqiang Ye, associate professor of pathology and laboratory medicine, and P. Michael Iuvone, professor of pharmacology and director of research at Emory Eye Center. Researchers from Morehouse School of Medicine and the University of Wisconsin contributed to the paper.
The discovery has implications for the study of how some antidepressants function and may also explain previous observations that N-acetylserotonin has antidepressant activity in animal models of depression.
"Our results suggest that the molecules and pathways involved in mood regulation and circadian rhythms are intertwined," Ye says.
A lack of BDNF, which pushes brain cells to grow and helps them resist stress, is thought to lie behind depression and several neurodegenerative diseases. Ye and his colleagues have been searching for chemicals that can mimic BDNF by activating TrkB, the receptor for BDNF on cells' surfaces.
Several widely prescribed antidepressants (selective serotonin reuptake inhibitors such as fluoxetine/Prozac) increase levels of serotonin in the brain, but the connections between serotonin levels and depression are complex. Because antidepressants seem to take weeks to display their effects, scientists have proposed that t
|Contact: Holly Korschun|