[Collagen synthesis after the implantation of polypropylene nets in the abdominal wall of young and old rats]. / Síntese de colágeno após a implantação de telas de polipropileno em parede abdominal de ratos jovens e velhos.

PURPOSE: Some investigators have stated that collagen synthesis is slower in elderly individuals, others have reported a reduction of collagen I and III synthesis, and still others have reported normal synthesis. The objective of the present study was to determine the collagen deposition occurring through the pores of a propylene net implanted in the abdominal wall of young adult rats compared to old rats. METHODS: Ten male rats aged 100 to 120 days and 10 rats aged 850 to 900 days were used. Under inhalatory anesthesia, a median incision was made in the ventral abdominal wall and a 4 cm2 gap was formed. The muscle-aponeurosis plane was removed and the peritoneal plane was maintained. The gap was corrected with a polypropylene mesh fixed with separate 5.0 polypropylene sutures and the skin margins were joined. The animals were sacrificed 30 days later and the ventral abdominal wall with the prosthesis was removed. The flap with the graft was divided into 2 parts, one for the traction assay and the other for histopathological study. The sections obtained were stained with hematoxylin-eosin and Sirius-red and examined under a polarized light microscope using the Image Plus software. RESULTS: The traction assay did not demonstrate a significant difference in resistance between groups. An acute-chronic inflammatory reaction with large quantities of giant foreign body cells was present at similar intensity in both groups, the same being observed for total collagen concentration (p=0.1440) and type I collagen concentration (p=0.3981). In contrast, type III collagen concentration was higher in the sections from old animals (p=0.0364). CONCLUSIONS: These results permit us to conclude that aging does not impair the resistance gain or collagen deposition, although a delayed tissue maturation occurs.