Changes in fatty acid desaturation in hepatic and intestinal tissues induced by intestinal resection

We have studied the activities of delta 9, delta 6 and delta 5 desaturases in rat liver and jejunum when the entero-hepatic circulation was interrupted by either 50 or 75% intestinal resection. Desaturase activities in caecal mucosa were also determined in control and operated rats. Distal small bowel resection significantly altered the activities of desaturase enzymes in liver, jejunum and caecum. Thus, the delta 9 desaturase activity was lower in hepatic microsomes from operated animals, and this decrease was not related to the extent by which the intestine was removed. However, a significant increase in both delta 6 and delta 5 desaturases was found in these animals compared to sham-operated rats, the increase in both desaturases being higher after 75% than after 50% intestinal resection. The activities of delta 9 and delta 5 desaturases were significantly increased in jejunal mucosa of resected rats. The activity of delta 6 desaturase was increased only in 50% resected-animals. An increase in delta 6 desaturase activity was observed in caecal mucosa after resection, together with a decrease in delta 9 desaturase and no change in delta 5 desaturase activities. Enzyme activities were highest in the liver relative to the activity in jejunal and caecal homogenates. In sham rats, the caecal mucosa showed higher delta 9 and delta 6 but lower delta 5 desaturase activities than in jejunal mucosa.