Seasonal rhythms of the indolamine content in the epiphysis of rats
Bondarenko, L.A.
Biulleten' Eksperimental'noi Biologii i Meditsiny 100(8): 137-139
1985
ISSN/ISBN: 0365-9615 PMID: 2411309 Document Number: 261655
Pineal function was studied in Wistar pubertal male rats in summer and winter. It was demonstrated that the pineal weight is inversely related to the day length, increasing in winter and reducing in summer. In winter pineal serotonin is actively metabolized via N-acetylation and subsequent ortho-methylation to form N-acetyl serotonin and melatonin as well as via oxidative deamination followed by ortho-methylation to form 5-hydroxyindolacetic and 5-methoxyindolacetic acids. In summer serotonin metabolism in the pinealocytes changes to direct ortho-methylation of serotonin to form 5-methoxytryptamine. The decreased level of N-acetyltransferase limits the formation of melatonin in the pineal gland in summer.