Abstract:To examine age-related changes in the morphology of intestinal brush border membrane (BBM; microvilli) and specific activities of intestinal BBM enzymes including alkaline phosphatase (ALP), γ-glutamyl transpeptidase (γ-GT), and disacchridase, four groups of Wistar rats were sacrificed at 2.5 wk, 5 wk, 5 mon and 23 mon. In an electron microscopic examination, morphologically a less dense BBM structure in the duodenum of rats aged 23 mon was observed than that of rats aged 5 mon. Specific activity of ALP in the duodenum from 5-mon-old rats was significantly higher than from rats aged 2.5 wk and 23 mon. The mucosal tissues from 5-wk-old rats had significantly higher specific activity of γ-GT than did tissues from the other ages. In sucrase and maltase specific activities, 5-mon-old rats had higher activities of these enzymes than other age groups, especially 2.5-wk-and 23-mon-old rats. There was also a significant effect of site on intestinal BBM enzyme activities in post-weanling rats. Regional gradients of ALP and γ-GT along the entire small intestine (duodenum>jejunum>ileum) were remarkable. Disaccharidase activities peaked in the jejunum and declined toward both the duodenum and ileum. Taken together the result obtained here suggested that 5-mon-old rats had the most elevated intestinal function. This result also strongly indicated that the structure of the intestinal BBM and development of intestinal BBM enzymes in Wistar rats were markedly influenced by age during the postnatal period. Key words: age, ALP, disaccharidase, γ-GT, microvilli the organs [4,13,23,31]. Among various organs, the epithelial cells lining the lumen of the gut are the first membrane barrier between the outside environment and the inside circulator in response to external and internal stimuli. The major mechanism associated with absorp-

The present study was designed to determine age-related changes in intestinal and hepatic antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and glutathione-S-transferase (GST), and lipid peroxidation in male Wistar rats (n = 8) aged 2 wk, 2.5 mon, 5 mon, 10 mon, and 23 mon. In the small intestine, cytosolic SOD, GSH-PX activities and lipid peroxidation were not affected by age, but intestinal GST activity was noticeably enhanced as age increased. In particular, intestinal GST activity in 23 mon old rats was 3 times as strong as that in 2 wk old rats. In the liver, the activity of hepatic cytosolic SOD was not affected by age, whereas GSH-PX and GST activities in rats aged 10 mon and 23 mon were much stronger than those in rats aged 2 wk, 2.5 mon, and 5 mon. The increased lipid peroxidation in 2.5 mon and 5 mon old rats was observed when compared with that of other groups. It is therefore concluded from the results presented here that age greatly increases GST activity in the small intestinal mucosae and increasing GSH-PX, GST activities and lipid peroxidation in the liver from male Wistar rats.

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