Atrophy and regeneration of rat calf muscles cause reversible changes in the number of nucleolar organizer regions

Evidence that also in nonproliferating cells the number of NORs is a marker of protein synthesis activity

L. Józsa, P. Kannus, M. Jarvinen, J. Isola, M. Kvist, M. Lehto

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

BACKGROUND: NORs are loops of DNA that transcribe to ribosomal RNA, and their number reflects the rDNA transcription, and, in this way, cell proliferation. EXPERIMENTAL DESIGN: The effect of muscle immobilization and remobilization on the number of nucleolar organizer regions (NORs) in the muscle cells and fibroblasts of rat calf muscles was studied histologically using a silver-staining technique (AgNOR). RESULTS: In muscle-cell nuclei, immobilization of 3 weeks produced a significant decrease in the number of AgNORs per nucleus. This phenomenon was reversible since, free remobilization of 4 weeks and especially intensified remobilization (free mobilization of 1 week plus treadmill running of 3 weeks) produced significant increase in the AgNOR counts. The treadmill running also produced a significant increase in the number of AgNORs in the muscle cells of contralateral (nonimmobilized) limbs. In intramuscular fibroblast nuclei, immobilization caused, in turn, a steady increase in the AgNOR count, the change being significant after 3 weeks. Free remobilization returned the count towards controls, and intensified remobilization returned it to the control level. CONCLUSIONS: Previous studies have shown that in the muscle cells immobilization decreases and remobilization (training) increases intracellular protein synthesis and that in the fibroblasts the opposite happens (immobilization increases and remobilization decreases intramuscular connective tissue formation). Our study gives indirect evidence that the number of NORs is a marker of ribosomal protein synthesis activity in non-proliferating cells. The cell- proliferation activity was proved to be zero using a proliferating-cell- nuclear-antigen technique.

Original languageEnglish
Pages (from-to)231-237
Number of pages7
JournalLaboratory Investigation
Volume69
Issue number2
Publication statusPublished - 1993

Fingerprint

Nucleolus Organizer Region
Immobilization
Atrophy
Regeneration
Cell Count
Muscle Cells
Muscles
Fibroblasts
Proteins
Running
Cell Proliferation
Silver Staining
Ribosomal RNA
Proliferating Cell Nuclear Antigen
Protein Biosynthesis
Ribosomal DNA
Cell Nucleus
Connective Tissue
Extremities
nucleolar organizer region associated proteins

Keywords

  • Colloidal-silver staining
  • Fibroblasts
  • Immobilization
  • Muscle cells
  • Protein synthesis
  • Remobilization

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

Cite this

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title = "Atrophy and regeneration of rat calf muscles cause reversible changes in the number of nucleolar organizer regions: Evidence that also in nonproliferating cells the number of NORs is a marker of protein synthesis activity",
abstract = "BACKGROUND: NORs are loops of DNA that transcribe to ribosomal RNA, and their number reflects the rDNA transcription, and, in this way, cell proliferation. EXPERIMENTAL DESIGN: The effect of muscle immobilization and remobilization on the number of nucleolar organizer regions (NORs) in the muscle cells and fibroblasts of rat calf muscles was studied histologically using a silver-staining technique (AgNOR). RESULTS: In muscle-cell nuclei, immobilization of 3 weeks produced a significant decrease in the number of AgNORs per nucleus. This phenomenon was reversible since, free remobilization of 4 weeks and especially intensified remobilization (free mobilization of 1 week plus treadmill running of 3 weeks) produced significant increase in the AgNOR counts. The treadmill running also produced a significant increase in the number of AgNORs in the muscle cells of contralateral (nonimmobilized) limbs. In intramuscular fibroblast nuclei, immobilization caused, in turn, a steady increase in the AgNOR count, the change being significant after 3 weeks. Free remobilization returned the count towards controls, and intensified remobilization returned it to the control level. CONCLUSIONS: Previous studies have shown that in the muscle cells immobilization decreases and remobilization (training) increases intracellular protein synthesis and that in the fibroblasts the opposite happens (immobilization increases and remobilization decreases intramuscular connective tissue formation). Our study gives indirect evidence that the number of NORs is a marker of ribosomal protein synthesis activity in non-proliferating cells. The cell- proliferation activity was proved to be zero using a proliferating-cell- nuclear-antigen technique.",
keywords = "Colloidal-silver staining, Fibroblasts, Immobilization, Muscle cells, Protein synthesis, Remobilization",
author = "L. J{\'o}zsa and P. Kannus and M. Jarvinen and J. Isola and M. Kvist and M. Lehto",
year = "1993",
language = "English",
volume = "69",
pages = "231--237",
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T1 - Atrophy and regeneration of rat calf muscles cause reversible changes in the number of nucleolar organizer regions

T2 - Evidence that also in nonproliferating cells the number of NORs is a marker of protein synthesis activity

AU - Józsa, L.

AU - Kannus, P.

AU - Jarvinen, M.

AU - Isola, J.

AU - Kvist, M.

AU - Lehto, M.

PY - 1993

Y1 - 1993

N2 - BACKGROUND: NORs are loops of DNA that transcribe to ribosomal RNA, and their number reflects the rDNA transcription, and, in this way, cell proliferation. EXPERIMENTAL DESIGN: The effect of muscle immobilization and remobilization on the number of nucleolar organizer regions (NORs) in the muscle cells and fibroblasts of rat calf muscles was studied histologically using a silver-staining technique (AgNOR). RESULTS: In muscle-cell nuclei, immobilization of 3 weeks produced a significant decrease in the number of AgNORs per nucleus. This phenomenon was reversible since, free remobilization of 4 weeks and especially intensified remobilization (free mobilization of 1 week plus treadmill running of 3 weeks) produced significant increase in the AgNOR counts. The treadmill running also produced a significant increase in the number of AgNORs in the muscle cells of contralateral (nonimmobilized) limbs. In intramuscular fibroblast nuclei, immobilization caused, in turn, a steady increase in the AgNOR count, the change being significant after 3 weeks. Free remobilization returned the count towards controls, and intensified remobilization returned it to the control level. CONCLUSIONS: Previous studies have shown that in the muscle cells immobilization decreases and remobilization (training) increases intracellular protein synthesis and that in the fibroblasts the opposite happens (immobilization increases and remobilization decreases intramuscular connective tissue formation). Our study gives indirect evidence that the number of NORs is a marker of ribosomal protein synthesis activity in non-proliferating cells. The cell- proliferation activity was proved to be zero using a proliferating-cell- nuclear-antigen technique.

AB - BACKGROUND: NORs are loops of DNA that transcribe to ribosomal RNA, and their number reflects the rDNA transcription, and, in this way, cell proliferation. EXPERIMENTAL DESIGN: The effect of muscle immobilization and remobilization on the number of nucleolar organizer regions (NORs) in the muscle cells and fibroblasts of rat calf muscles was studied histologically using a silver-staining technique (AgNOR). RESULTS: In muscle-cell nuclei, immobilization of 3 weeks produced a significant decrease in the number of AgNORs per nucleus. This phenomenon was reversible since, free remobilization of 4 weeks and especially intensified remobilization (free mobilization of 1 week plus treadmill running of 3 weeks) produced significant increase in the AgNOR counts. The treadmill running also produced a significant increase in the number of AgNORs in the muscle cells of contralateral (nonimmobilized) limbs. In intramuscular fibroblast nuclei, immobilization caused, in turn, a steady increase in the AgNOR count, the change being significant after 3 weeks. Free remobilization returned the count towards controls, and intensified remobilization returned it to the control level. CONCLUSIONS: Previous studies have shown that in the muscle cells immobilization decreases and remobilization (training) increases intracellular protein synthesis and that in the fibroblasts the opposite happens (immobilization increases and remobilization decreases intramuscular connective tissue formation). Our study gives indirect evidence that the number of NORs is a marker of ribosomal protein synthesis activity in non-proliferating cells. The cell- proliferation activity was proved to be zero using a proliferating-cell- nuclear-antigen technique.

KW - Colloidal-silver staining

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SN - 0023-6837

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