Endogenous corticosterone rather than dietary sucrose as a modulator for intestinal sucrase activity in artificially reared rat pups.

The effects of sucrose and corticosterone on the expression of intestinal sucrase activity in preweanling rat pups were studied using an artificial rearing (AR) technique. When AR rat pups were isocalorically fed diets containing lactose or sucrose, or a carbohydrate-free diet from d 12-16, jejunal and ileal sucrase and maltase activities were induced to similar levels in all AR rats, whereas ileal lactase activity was precociously decreased. In separate experiments, enzyme activities were measured in ileal isografts subcutaneously implanted in littermates at birth. In AR rats fed the lactose diet, these isografts showed sucrase and maltase activities comparable with those of host ileum and also to isografts from AR rats fed the sucrose diet. In contrast, lactase activity was significantly higher in isografts than host ileum in all AR rats. Serum corticosterone levels were significantly elevated in AR rats for 24 h after intragastric cannular implantation. Precocious expression of ileal sucrase activity occurred in corticosterone treated, but not in untreated, adrenalectomized AR rats. In conclusion, dietary sucrose has no specific role in enhancing intestinal sucrase activity, and endogenous corticosterone is responsible for the induction of sucrase activity in AR rats.