title: Effect of aging on liver regeneration in rats.
abstract: OBJECTIVE
  Regeneration and/or healing of tissues is believed to be more difficult in elderly people. The liver is one of the most complex organs in the human body, and is involved in a variety of functions. Liver regeneration is the body's protection mechanism against loss of functional liver tissue. The aim of this study is to identify the regenerative capacity of the liver in older animals and to compare it with that of young adult animals.
  
  
  METHODS
  Thirty-four Wistar rats were used, of which 17 were 90 days old (young animals) and 17 were 460 days old (old animals). Approximately 70% of the liver was surgically removed. Examinations were carried out after 24 hours and on day 7, using 3 methods: KWON et al.'s formula to identify increase in volume; mitotic figure count in 5 fields; and the percentage of PCNA-positive nuclei in 5 fields.
  
  
  RESULTS
  The increase in volume of the remaining liver was greater in the young animals after both 24 hours (p=0.0006) and on day 7 (p=0.0000). Histological cuts showed a greater mitotic figure count in young animals evaluated after 24 hours (p=0.0000). Upon evaluation on day 7, recovery was observed in the old animals. This recovery was similar to that of the young ones (p=0.2851). The PCNA-positive nucleus count was greater in the young animals' liver cuts after 24 hours (p=0.0310), and, while it had decreased in young animals by day 7, recovery was observed in the older animals (p=0.0298).
  
  
  CONCLUSIONS
  The data confirm that age is related to delay in liver regeneration in rats.
authors.affiliation: Surgical Techniques and Experimental Surgery Program, School of Medicine, Department of Surgery, Federal University of Paraná, Brazil. biondo@avalon.sul.com.br
authors.forename: Maria de Lourdes Pessole
authors.initials: Mde L
authors.lastname: Biondo-Simões
authors.forename: Jorge Eduardo Fouto
authors.initials: JE
authors.lastname: Matias
authors.forename: Guilherme Ramina
authors.initials: GR
authors.lastname: Montibeller
authors.forename: Letícia Cristina Dalledone
authors.initials: LC
authors.lastname: Siqueira
authors.forename: Eduardo da Silva
authors.initials: Eda S
authors.lastname: Nunes
authors.forename: Cristiano Antonio
authors.initials: CA
authors.lastname: Grassi
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D002452:Cell Count; D004195:Disease Models, Animal; D006498:Hepatectomy; D008099:Liver / Q000502:physiology / Q000601:surgery / Q000648:ultrastructure; D008115:Liver Regeneration / Q000502:physiology*; D008297:Male; D008938:Mitosis; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D014945:Wound Healing / Q000502:physiology
chemical_list: D018809:Proliferating Cell Nuclear Antigen