title: Re-adaptation of the esophageal mucosa of rats to protracted stress.
abstract: BACKGROUND
  Previous studies showed that the DNA synthesis (DS) in the esophagus of rats significantly increased at 4 weeks of stress, but decreased to normal values at 8 weeks. The possibility that this DS adaptation (DSA) could be maintained beyond 8 weeks was explored.
  
  
  METHODS
  Sixty-five rats were investigated: 60 were transported to the stress laboratory (30 were water-plunged and 30 were controls) for 8 weeks. After 8 weeks, groups of stressed and control animals (n = 5) were allowed to rest one, two, three and four weeks, ending with single water-plunging or sham-handling. All animals (including 5 untreated) received i.p. injection of 3H-thymidine before sacrifice. The ratio radioactive DNA/total DNA reflected the DS of the esophagus. The isotope mainly labeled mucosal cells.
  
  
  RESULTS
  DS significantly increased at 10 and 11 weeks (p < 0.05), but decreased below 8 week values at 12 weeks.
  
  
  CONCLUSIONS
  DSA values at 8 stress weeks did not prevail since DS substantially increased in stressed rats at 10 and 11 weeks. At 12 weeks, DS re-adaptation (DSRA) occurred. Importantly, it took 8 weeks to achieve DSA, but only 4 weeks to accomplish DSRA. Control animals also showed DS fluctuations, but to a lower degree. The model described may prove of value in studies aimed to abate the disparate fluctuations of DNA synthesis in the esophageal mucosa during the various phases of protracted stress.
authors.affiliation: Gastrointestinal and Liver Research Laboratory, Department of Pathology, Karolinska Institute and Hospital, Stockholm, Sweden.
authors.forename: C A
authors.initials: CA
authors.lastname: Rubio
authors.forename: M
authors.initials: M
authors.lastname: Sveander
authors.forename: J
authors.initials: J
authors.lastname: Lagergren
mesh_terms: D000208:Acute Disease; D000222:Adaptation, Physiological; D000818:Animals; D002908:Chronic Disease; D004261:DNA Replication; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D004947:Esophagus / Q000473:pathology*; D006965:Hyperplasia; D007101:Immersion / Q000009:adverse effects; D008297:Male; D009092:Mucous Membrane / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012008:Recurrence; D013312:Stress, Physiological / Q000150:complications / Q000473:pathology*; D013550:Swimming