RESUMO
The aim of this study was to investigate the effect of aging on the regenerative capacity of the gastric mucosa after acute injury. This study was conducted on 36 male albino rats for the study of mucosal injury by using 2 M NaCI. The animals were equally divided into 3 subgroups aged 4, 12, 24 months. The animals in each subgroup were killed 1, 6, 24, and 48 hours after intake of NaCI. Paraffin sections were prepared from specimens of the gastric mucosa of rats and stained by Hx and E, PAS and Alcian blue/PAS. One hour postinjury, the gastric mucosa of young rats showed a lesion index of 70.1% and the grade of mucosal injury was classified as grade I. The gastric mucosa of old rats demonstrated a lesion index of 88.3%, and the mucosal injury was grade II. The gastric mucosa of senescent rats demonstrated a lesion index of 100% with mucosal injury of grade III. Six hours post-injury, the lesion index of young rat gastric mucosa was 10.7%, several areas of regeneration with groups of flattened cells covering most of the mucosal surface were observed and further expansion of the neck region was demonstrated. The gastric mucosa of old rats showed a lesion index of 26.5%, and regeneration was detected in some areas. In senescent rats, the lesion index was 74.9%, the neck region was expanded and the mucosal surface was still mostly exposed with no signs of regeneration. Twenty four hours post-injury, the mucosal surface of young rats showed complete regeneration with small, cubical cells having rounded nuclei. Partial re-establishment of the glandular structure pattern was also observed. On the other hand, the gastric mucosa of old rats showed a lesion index of 10.0%, and clumps of proliferating cells were seen covering most of the mucosal surface. The gastric mucosa of senescent rats showed a lesion index of 37% with only intermittent clusters of regenerating epithelial at the same time post-injury. Forty eight hours post-injury, the glandular structure of young rat gastric mucosa has been completely re-established and the regenerated epithelial cells appeared normal. The gastric mucosa of old rats also showed evidence of regeneration and partial re-establishment of the glandular architecture and gastric pits. However, gastric mucosa of senescent rats demonstrated a lesion index of 10.2%, partial healing with focal sites of healing failure and incompletely reestablished glandular architecture. Aging is associated with increased susceptibility of the gastric mucosa to injury and delayed repair process. Irritating foods and drugs such as NSAIs should be avoided in the elderly and if necessary, their dose should be adjusted and proper follow up should be provided to avoid severe gastric mucosal injuries