Melatonin synthesis in the retina and pineal gland of djungarian hamsters at different times of the year

Stephan Steinlechner, Ilona Baumgartner, Gabriela Klante, Russel J. Reiter

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Daily profiles of melatonin content in the retina of Djungarian hamsters were measured throughout the course of a year. Peak levels of retinal melatonin were found at various times of the day at different seasons. In a subsequent study we determined concurrently daily profiles of nine indole metabolites (tryptophan, 5-hydroxytryptophan, 5-hydroxytryptamin, 5-hydroxyindoleacetic acid, 5-hydroxytryptophol, N-acetylserotonin, melatonin, 5-methoxyindoleacetic acid and 5-methoxytryptophol) in samples of hamster retina and pineal gland at the four different seasons. Measurements were made using HPLC coupled to a coulometric electrode detection system. Large seasonal variations in the levels and daily rhythm amplitudes of the different indole metabolites were found in the pineal glands. Due to technical problems and unknown interfering substances only tryptophan and serotonin could be determined in the retinas at all four seasons. Despite this, the ability to measure levels of several metabolites in the same sample and in different tissues of the same animals permitted more accurate comparisons of the components involved in melatonin synthesis. Our data suggest that the level of retinal melatonin is regulated and controlled locally within the retina itself. However, long-term feedback mechanisms from other sources of melatonin are not excluded but are rather likely.

Original languageEnglish (US)
Pages (from-to)245-251
Number of pages7
JournalNeurochemistry International
Issue number3
StatePublished - Sep 1995


  • 5-HIAA, 5-hydroxyindoleacetic acid
  • 5-HT, serotonin
  • 5-HTP, 5-hydroxytryptophan
  • 5-MIAA, 5-methoxyindoleacetic acid, 5MTOH, 5-methoxytryptophol
  • 5HTOH, 5-hydroxytryptophol
  • HPLCEC, high-performance liquid chromatography coupled with electrochemical detection
  • NAS, N-acetylserotonin
  • NAT, N-acetyltransferase
  • Trp, tryptophan

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Cell Biology


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