Possible Interaction: Melatonin and Serotonin

“Generally, melatonin actions oppose those of serotonin.”

“Yoshioka et al. studied the effect of melatonin administration on the release of 5-hydroxytryptamine , 5-HIAA, DOPAC (3, 4-dihydroxyphenylacetic acid), and HVA in the suprachiasmatic nuclei of rats and reported that the release of the 5-HT metabolite and 5-HIAA was significantly reduced by this treatment.”

“Experiments using both exogenous treatment of serotonin and senescent detached leaves, which contain a pool of serotonin, significantly enhanced melatonin biosynthesis, indicating that endogenous serotonin levels play a bottleneck role in the pathway of melatonin biosynthesis.”

“Heavy fatigue of these patients was linked to the changes of levels and mutual ratio of melatonin and serotonin and regarding autoantibodies, mainly autoantibodies against steroid producing cells, namely against the particular cells of the layers of adrenal cortex played a role.”

“The urinary metabolites of serotonin suggest that the observed improvements were due to an increased use of serotonin to melatonin synthesis.”

“Release of GI melatonin from serotonin-rich enterochromaffin EC cells of the GI mucosa suggest close antagonistic relationship with serotonin (S) and seem to be related to periodicity of food intake.”

“Melatonin deficiency, increased serotonin level with disturbed melatonin-serotonin interactions and calmodulin antagonism by increased IQGAP1 may be responsible for progression of both types of spinal deformities in neurofibromatosis 1.”

“ Melatonin inhibited serotonin uptake by blood platelets at the high concentrations only ( > 10(-5) M with IC50 value of 1.1 x 10(-3) M) and had no effect at physiological concentrations.”

“Moreover, serotonin has been found to be a competitive inhibitor of melatonin binding to platelets.”

“This relationship is supported by the findings that melatonin regulates the activity of brainstem serotonin ( 5-HT ) neurons which characteristically cease to fire during REM sleep and which faciliate the development of REM sleep atonia.”

“ Melatonin inhibits several physiological processes in platelets including … aggregation phenomenon the release of ATP and serotonin (indexes of the platelet secretory mechanism), and the production of thromboxane B2 A generally greater, and dose-…, effect of nanomolar melatonin concentrations in the evening as compared to morning melatonin found in vivo.”