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Effects of single doses and daily melatonin treatments on serotonin metabolism in rat brain regions
Author(s) -
Miguez J. M.,
Martin F. J.,
Aldegunde M.
Publication year - 1994
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.1994.tb00129.x
Subject(s) - melatonin , endocrinology , medicine , serotonin , serotonergic , hypothalamus , preoptic area , thermoregulation , biology , chemistry , receptor
Miguez, JM, Martin F. J, Aldegunde M. Effects of single doses and daily melatonin treatments on serotonin metabolism in rat brain regions. J. Pineal Res. 1994; 17:170–176. Abstract The acute effects of two doses (0. 5 and 1 mg/kg) of melatonin on the levels of tryptophan, serotonin, and 5‐hydroxyin‐doleacetic acid in several rat brain regions were studied. Tryptophan content in the brain regions was unchanged by the treatments. Melatonin at a dosage of 0. 5 mg/kg increased medial hypothalamic serotonin levels at 60 and 90 min after the injection. However, the dose of 1 mg/kg increased the levels of this amine or its metabolite in the preoptic area‐anterior hypothalamus, medial and posterior hypothalamus, amygdala, and midbrain. These results suggest a specific regional sensitivity to melatonin as well as a dose‐dependent response. The stimulatory melatonin effect on the serotoninergic system was also observed after a daily treatment with this hormone (0. 5 mg/kg, twice daily during 10 days) in both intact or pinealectomized rats. In intact rats, melatonin treatment increased the levels of 5‐hydroxyindole‐3‐acetic acid in the preoptic area‐anterior hypothalamus and medial hypothalamus, while in pinealectomized rats melatonin increased the serotonin content in the medial hypothalamic region. The data support the idea that melatonin has a selective action on serotonin metabolism in regions that contain serotoninergic terminals, especially at medial hypothalamic level.