The influence of some pterins on the circadian rhythmicity of hydroxyindole-O-methyl transferase in the pineal gland of 42-day old male Wistar rats.
The influence of three pterin derivatives on the diurnal fluctuations of HIOMT (hydroxyindole-O-methyl transferase) activity was studied in the isolated pineal glands of 42-day old male Wistar rats during the month of October. The method used permitted the separate determination of four HIOMT activities. --Reduced neopterin stimulated the methylation of the substances, 5-HTP, 5-HT and 5-HIAA (see abbreviations in Material and methods), during the night. HIOMT action on the combinations N-Ac-5-HT/5-HTL was shifted to a later moment in the dark period. --Pterin-6-aldehyde stimulated HIOMT action on 5-HT during the daytime. HIOMT action on the substrates 5-HTP, 5-HIAA and N-Ac-5-HT/5-HTL was shifted towards an earlier period. --Isoxanthopterin did not exert any influence on diurnal variation in the four HIOMT activities. It may be concluded that reduced neopterin and pterin-6-aldehyde influenced the activity and the circadian rhythmicity of 5-methoxyindole synthesis. Those alterations might be important in the regulation of reproduction.
D006916:5-Hydroxytryptophan / Q000378:metabolism; D000121:Acetylserotonin O-Methyltransferase / Q000378:metabolism*; D000818:Animals; D001708:Biopterins / Q000031:analogs & derivatives / Q000494:pharmacology; D002940:Circadian Rhythm / Q000187:drug effects*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D006917:Hydroxytryptophol / Q000378:metabolism; D008297:Male; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism*; D019798:Neopterin; D011621:Pteridines / Q000494:pharmacology; D011622:Pterins / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000031:analogs & derivatives / Q000378:metabolism; D014976:Xanthopterin / Q000494:pharmacology
D011621:Pteridines; D011622:Pterins; D006917:Hydroxytryptophol; D001708:Biopterins; D012701:Serotonin; C008217:isoxanthopterin; D006897:Hydroxyindoleacetic Acid; D019798:Neopterin; C005926:2-amino-4-hydroxy-6-formylpteridine; D006916:5-Hydroxytryptophan; D008780:Methyltransferases; D000121:Acetylserotonin O-Methyltransferase; C006389:N-acetylserotonin; D014976:Xanthopterin