Infant colic: the effect of serotonin and melatonin circadian rhythms on the intestinal smooth muscle.
It is hypothesized that in the evening, peak serotonin concentration causes intestinal cramps associated with colic because serotonin increases intestinal smooth muscle contractions. Melatonin has the opposite effect of relaxing intestinal smooth muscles. Both serotonin and melatonin exhibit a circadian rhythm with peak concentrations in the evening. However, serotonin intestinal contractions are unopposed by melatonin during the first 3 months because only serotonin circadian rhythms are present at birth. Melatonin circadian rhythms appear at 3 months of age. The cramps of colic disappear at 3 months of age.
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D002940:Circadian Rhythm / Q000502:physiology*; D003085:Colic / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007422:Intestines / Q000503:physiopathology; D008550:Melatonin / Q000502:physiology; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology; D009130:Muscle, Smooth / Q000503:physiopathology; D012701:Serotonin / Q000502:physiology
D012701:Serotonin; D008550:Melatonin