Influence of starvation on sucrase regulation by dietary sucrose in the rat.

We have studied the action of sucrose on jejunal sucrase activity. Rats (175 g) were first starved or fed a digestible carbohydrate-free diet for 60 h and then fed a high sucrose diet for varying times up to 84 h. 1) Rats starved for 60 h showed mucosal atrophy with a decrease in protein content/10 cm (18.00 +/- 1.4 versus 40.1 +/- 3 mg (controls p less than 0.001) and in villus height (357 +/- 18 versus 526 +/- 5 microns, p less than 0.001) which was fully repaired only after 60 h on the sucrose diet (528 +/- 11 microns). Rats on digestible carbohydrate-free diet showed no mucosal atrophy. 2) Starved rats had a delayed (60 h) sucrase activity response to sucrose (53 +/- 7 versus 122 +/- 4 microns/mg protein, p less than 0.001). Maximum activity was obtained after 12 h on sucrose diet in rats maintained on the carbohydrate-free diet: 38 +/- 1 versus 108 +/- 2.3 microns/mg protein, p less than 0.001. 3) Villus and crypt cell analysis after starvation and 12 h on a high sucrose diet localized the increase in sucrase activity to the villus-crypt junction. No change occurred in the upper villus. The increase was complete all along the villus by 36 h. In contrast, after the carbohydrate-free diet, sucrase activity increased maximally at all levels of the villus by 12 h on the high sucrose diet.(ABSTRACT TRUNCATED AT 250 WORDS)