Stimulation of disaccharidase activities in the jejunal brush border membrane of adult rat by total parenteral nutrition. Effects of thyroid hormones.

This study examined the morphological and functional adaptations occurring in the jejunum of adult rats fed totally by parenteral nutrition during a 4-day period. Comparison was made with sham-operated animals receiving orally a similar isocaloric diet. The intravenously fed rats exhibited a 20% shortening of the villus height. The specific activity of aminopeptidase showed remarkable stability in all conditions. A major stimulation (2.5-fold) was measured for lactase-specific activity. Daily administration of thyroxine completely inhibited the rise of lactase activity. Thyroidectomy caused a significant increase of lactase activity in the orally fed controls, but did not exert any synergistic effect with parenteral nutrition on intestinal enzyme activities. In our experimental conditions intravenous feeding led to a 3-fold decrease in the concentration of thyroid hormones detected in the serum. The results show that total parenteral nutrition leads to a stimulation of the specific activity of brush border lactase in the intestine of adult rat which might be related to the level of thyroid hormones.