2 2 Endocrine Factors in Food Absorption 



influence on intestinal absorption is concerned, several experiments were per- 

 formed in which, after lowering intestinal absorption by removal of one gland 

 of internal secretion, the efl^ect of administration of the hormone of another 

 gland was determined. Russell"^ had observed that daily administration of 

 very small amounts (o.oi to 0.02 mg.) of thyroxin to hypophysectomized rats 

 increased their rate of absorption for dextrose to normal but did not afliect 

 other phases of carbohydrate metabolism, although the amount of oxidation 

 of carbohydrates was increased approximately in proportion to the increase 

 in oxygen consumption. This experiment appears to support the conception 

 that hypophysectomy affects intestinal absorption through lack of the thyro- 

 trophic hormone. 



By administering thyroxin to a number of adrenalectomized animals in 

 doses sufficient to render normal rats hyperthyroid, we also were successful in 

 bringing their rate of intestinal absorption for dextrose up to normal. The 

 fact that relatively large amounts of thyroxin (o. 1 mg.) were required to pro- 

 duce this effect while small amounts were ineffective was interpreted as indicat- 

 ing that thyroxin produced an increase in the rate of absorption for dextrose, 

 not by supplying a deficiency, but by its presence in excessive amounts. 



When large amounts of adrenal cortical extract (Wilson) were administeied 



to thyroidectomized rats, no increase in intestinal absorption of dextrose took 



place. The same was true when adrenalectomized female rats were injected 



with large doses of estrone. 



Summary 



1. Thyroidectomy significantly diminishes intestinal absorption of utilizable 

 carbohydrates and of fats in the rat. Administration of thyroxin markedly 

 increases the rate of intestinal absorption for these foodstuffs in normal rats 

 and in animals subjected to removal of the hypophysis or of the adrenals. 

 Since administration of thyroxin does not affect the absorption of xylose, 

 alanin, calcium lactate, or thiamine chloride we conclude that the thyroid 

 hormone is a stimulant for intestinal absorption of substances susceptible to 

 phosphorylation. 



2. Adrenalectomy significantly decreases intestinal absorption of utilizable 

 carbohydrates and of fats in the rat. Administration of large amounts of 

 adrenal cortical hormone to normal, to pancreatectomized, and to thyroidec- 

 tomized rats has no effect on absorption of these substances from the intestine. 

 The addition of salt to drinking water restores the intestinal absorption of 

 adrenalectomized rats to normal. These data indicate that the hormone of the 

 adrenal cortex has no direct effect on intestinal absorption but that its absence 

 may lower intestinal absorption by impairing the general health of the animal 

 or by disturbing its metabolism of sodium chloride. 



3. The rate of intestinal absorption for utilizable sugars, but not for calcium 

 lactate, is higher in female than in male rats. Spaying reduces the intestinal 

 absorption of dextrose in the young female to the level of the male. Castration 

 in the male has no effect on intestinal absorption. Administration of large 



