title: Seasonal variations in HIOMT activity during the night in the pineal gland of 21 day old male Wistar rats.
abstract: In the pineal of 21-day old male Wistar rats hydroxyindole-O-methyltransferase (HIOMT) activities involved in the synthesis of several 5-methoxyindoles were determined during the night in April, June, October and January. A high HIOMT activity for the synthesis of melatonin/5-methoxytryptophol was determined in the months of January and April. In June and October a decrease was observed. The activity maxima coincide with peaks of activity found for the synthesis of 5-methoxytryptophan. Synthesis of 5-methoxytryptamine occurred only in June and October, whereas the synthesis of 5-methoxyindole-3-acetic acid occurred only in January. From these results it may be concluded that January and April are the most active months of those tested for the melatonin/5-methoxytryptophol synthesis in the rat pineal gland. A possible physiological role of the 5-methoxyindoles other than melatonin and 5-methoxytryptophol is discussed.
mesh_terms: D008735:5-Methoxytryptamine / Q000096:biosynthesis; D000121:Acetylserotonin O-Methyltransferase / Q000378:metabolism*; D000818:Animals; D002940:Circadian Rhythm; D007211:Indoles / Q000096:biosynthesis; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008550:Melatonin / Q000096:biosynthesis; D008780:Methyltransferases / Q000378:metabolism*; D010870:Pineal Gland / Q000201:enzymology*; D051381:Rats; D012621:Seasons; D014364:Tryptophan / Q000031:analogs & derivatives / Q000096:biosynthesis
chemical_list: D007211:Indoles; D007527:Isoenzymes; C027986:5-methoxytryptophan; D008735:5-Methoxytryptamine; C002465:methoxytryptophol; D014364:Tryptophan; D008780:Methyltransferases; D000121:Acetylserotonin O-Methyltransferase; D008550:Melatonin