Comparison of the Rat Pinealocyte Ultrastructure With Melatonin Concentrations During Daytime and at Night

Authors

  • M. Karasek,

    Corresponding author
    1. Laboratory of Electron Microscopy, Department of Pathological Anatomy, Institute of Pathology, Medical Academy, Lodz, Poland (M. K.); Department of Pharmacology, Chemotherapy and Toxicology, University of Milan, Milan, Italy (B. S., V. L., F. S., G. E., M. M., F. F.)
      Address requests for reprints to Prof. Dr. Michal Karasek, Laboratory of Electron Microscopy, Medical Academy, 91-425 Lodz, Sterlinga 5, Poland
    Search for more papers by this author
  • B. Stankov,

    1. Laboratory of Electron Microscopy, Department of Pathological Anatomy, Institute of Pathology, Medical Academy, Lodz, Poland (M. K.); Department of Pharmacology, Chemotherapy and Toxicology, University of Milan, Milan, Italy (B. S., V. L., F. S., G. E., M. M., F. F.)
    Search for more papers by this author
  • V. Lucini,

    1. Laboratory of Electron Microscopy, Department of Pathological Anatomy, Institute of Pathology, Medical Academy, Lodz, Poland (M. K.); Department of Pharmacology, Chemotherapy and Toxicology, University of Milan, Milan, Italy (B. S., V. L., F. S., G. E., M. M., F. F.)
    Search for more papers by this author
  • F. Scaglione,

    1. Laboratory of Electron Microscopy, Department of Pathological Anatomy, Institute of Pathology, Medical Academy, Lodz, Poland (M. K.); Department of Pharmacology, Chemotherapy and Toxicology, University of Milan, Milan, Italy (B. S., V. L., F. S., G. E., M. M., F. F.)
    Search for more papers by this author
  • G. Esposti,

    1. Laboratory of Electron Microscopy, Department of Pathological Anatomy, Institute of Pathology, Medical Academy, Lodz, Poland (M. K.); Department of Pharmacology, Chemotherapy and Toxicology, University of Milan, Milan, Italy (B. S., V. L., F. S., G. E., M. M., F. F.)
    Search for more papers by this author
  • M. Mariani,

    1. Laboratory of Electron Microscopy, Department of Pathological Anatomy, Institute of Pathology, Medical Academy, Lodz, Poland (M. K.); Department of Pharmacology, Chemotherapy and Toxicology, University of Milan, Milan, Italy (B. S., V. L., F. S., G. E., M. M., F. F.)
    Search for more papers by this author
  • F. Fraschini

    1. Laboratory of Electron Microscopy, Department of Pathological Anatomy, Institute of Pathology, Medical Academy, Lodz, Poland (M. K.); Department of Pharmacology, Chemotherapy and Toxicology, University of Milan, Milan, Italy (B. S., V. L., F. S., G. E., M. M., F. F.)
    Search for more papers by this author

Address requests for reprints to Prof. Dr. Michal Karasek, Laboratory of Electron Microscopy, Medical Academy, 91-425 Lodz, Sterlinga 5, Poland

Abstract

The aim of this study was to investigate the ultrastructure of rat pinealocyte during daytime (1600 h) and at night (0100 h) and to compare these observations with serum melatonin levels in the same animals. In addition, pineal melatonin concentrations were determined in other animals. Both serum and pineal melatonin concentrations were significantly higher at night than during daytime (34 and 21 times, respectively). Sizes of pinealocytes, their nuclei, and nucleoli, as well as cross-sectional areas of mitochondria and granular endoplasmic reticulum were also higher at night than during daytime, whereas areas of lysosomes, Golgi apparatus, and vacuoles containing flocculent material did not differ at the time points studied. In contrast, the number of dense-core vesicles was higher during daytime. The results of the present study show that morphological patterns of higher metabolic activity of the rat pinealocyte at night when compared to those during daytime correlate with melatonin concentrations.

Ancillary