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Influence of Serotonin and Melatonin on Some Parameters of Gastrointestinal Activity
Author(s) -
Bubenik George A.,
Dhanvantari Savita
Publication year - 1989
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.1989.tb00909.x
Subject(s) - serotonin , melatonin , endocrinology , medicine , tonic (physiology) , in vivo , 5 ht receptor , acetylcholine , in vitro , chemistry , receptor , biology , biochemistry , microbiology and biotechnology
In vitro melatonin (M) reduced the tone of gut muscles and counteracted the tonic effect of serotonin (5‐HT). In vivo 0.1 to 4 mg of 5‐HT (contained in beeswax implants) decreased the food transit time (FTT) in a dose‐dependent manner, but higher doses (5 and 6 mg) increased the FTT. Melatonin injected intraperitoneally into mice bearing 5‐HT implants (2 mg per animal) blocked partly the serotonin effect and increased FTT by 50%; however, no dose‐dependent effect was observed when doses between 0.01 and 1 mg were used. Surprisingly, M injected into intact mice decreased FTT to levels comparable to those observed in 5‐HT implanted, M‐treated mice. Again, this significant decrease was not dose‐dependent between 0.02 and 1 mg. Although in vitro the maximal inhibition of serotonin‐induced spasm was achieved when the M: 5‐HT ratio was 50–100: 1, in vivo the effective ratio was about 1: 1. This may indicate that part of M action on the gut movement is mediated by extraintestinal mechanisms. A hypothetical, counterbalancing system of M and 5‐HT regulation of gut activity (similar to adrenaline‐acetylcholine system) is proposed.