Influence of the thyroid and adrenal glands on the growth of the intestine of the suckling rat, and on the development of intestinal alkaline phosphatase and disaccharidase activities

Abstract

Abstract Previous investigations have shown that cortisone or thyroxine can promote maturation of the intestinal epithelium in rats hypophysectomized at six days of age. This indication that either the thyroid or the adrenocortical hormone can act in the absence of the other has been pursued by study of intestinal maturation in rats deprived of the thyroid or adrenal glands during the suckling period. At 24 days of age, rats that have been thyroidectomized at six days retain the short villi and low mitotic index characteristic of neonatal life. Thyroxine elevates the mitotic index; neither thyroxine nor cortisone promote lengthening of the villi, but both cause some deepening of the crypts. Duodenal alkaline phosphatase and jejunal maltase remain at very low levels, but sucrase, which is absent at six days, does appear in the thyroidectomized pups at 24 days. Thyroxine raises phosphatase and maltae activity to the normal 24‐day level, but cortisone is only partly effective. Sucrase is raised above the normal maximum by cortisone but not by thyroxine. After adrenalectomy at 14 days, cortisone corrects deficiencies in villus height, crypt depth, and mitotic index, but thyroxine is without effect. Phosphatae, maltase, and sucrase activities rise only to subnormal levels in adrenalectomized pups. Thyroxine restores phosphatase activity to the control level, but is only partly successful in normalizing disaccharidase activities. Periodic acid‐Schiff stainability of the brush border is weak in specimens deprived of either thyroid or adrenals. Both thyroxine and cortisone restore normal intensity after thyroidectomy; after adrenalectomy only cortisone was able to restore normal stainability. Plasma corticosteroid concentration is elevated by thyroxine only if the hypophysis is present. These results demonstrate that the intestinal epithelium is able to respond to each hormone in the absence of the other.