Modulation by Thyroxine of the Amount of Lactase Protein in the Jejunum of Adult Rats

Abstract
Adult rats starved for 48 h received a daily injection of thyroxine over a 3-day period before they were killed. When compared to nourished animals, starvation provoked a 4- to 5-fold increase in immunoreactive lactase protein, which paralleled a similar stimulation of lactase activity in the brush border membranes of the proximal jejunum. Exogenous thyroxine completely inhibited the starvation-induced increase in immunoreactive lactase protein in both the intracellular and the brush border membranes.