The effects of melatonin, N-acetylserotonin, and 6-hydroxymelatonin on the ultrastructure of the pinealocytes of the Syrian hamster (Mesocricetus auratus)

Anna Zieliñska, Jacek Świȩtosławski, Russel J. Reiter, Michał Karasek

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Objectives: The aim of this study was to examine the effects of melatonin as well as of its precursor (N-acetylserotonin) and metabolite (6-hydroxymelatonin) on the ultrastructure of the pinealocytes of the Syrian hamster. Material and methods: The pineal glands of 2-month-old male Syrian hamsters were examined. The animals were divided into the following groups of four animals each: group 1-melatonin treatment; group 2-N-acetylserotonin treatment; group 3-6-hydroxymelatonin treatment (all substances given subcutaneously at doses of 25 mg per animal between 16.00 and 17.00 h daily for seven weeks). Group 4 was given solvent treatment only and served as controls. The animals were killed by decapitation between 09:00 and 10.00 h. Routine electron microscopical techniques were used to obtain quantitative data on pinealocyte ultrastructure. Results: Melatonin administration did not influence the size of the hamster pinealocytes, whereas administration of N-acetylserotonin and 6-hydroxymelatonin caused a significant reduction in cell size in comparison to the melatonintreated and control groups. There were changes in the relative volumes of the mitochondria, Golgi apparatus and lysosomes in the pinealocytes of the studied groups, while the volumes of granular endoplasmic reticulum and lipid droplets were unchanged. The dense-core vesicles were more numerous in the pinealocytes of the melatonin and 6-hydroxymelatonin-treated groups in comparison to those of animals treated with N-acetylserotonin or the controls. Conclusions: The changes observed in the ultrastructure of hamster pinealocytes indicate that administration of melatonin as well as of its precursor or metabolite influences the morphology of these cells and also, perhaps, their secretory activity.

Original languageEnglish (US)
Pages (from-to)2-6
Number of pages5
JournalEndokrynologia Polska
Volume57
Issue number1
StatePublished - Dec 1 2006

Keywords

  • 6-hydroxymelatonin
  • Melatonin
  • N-acetylserotonin
  • Pineal gland
  • Pinealocyte
  • Quantitative analysis
  • Syrian hamster
  • Ultrastructure

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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