Endocrinology, Vol 108, 1138-1141, Copyright © 1981 by Endocrine Society

ARTICLES

Retarded growth rate caused by glucocorticoid treatment or dietary restriction: associated changes duodenal, jejunal, and ileal calcium absorption in the chick

J Fox and H Heath 3d

Calcium (Ca) absorption is reportedly stimulated in the ileum of glucocorticoid-treated rats. Our study was designed to investigate this phenomenon in the chick; to determine to what extent any stimulation might compensate for inhibition of Ca absorption in the duodenum; and to compare any changes seen with those caused by growth retardation induced by dietary restriction alone. We assessed CA absorption from different sites in the intestine of chicks treated with betamethasone (BM; 25 micrograms/kg . day for 14 days), or diet-restricted to permit growth at the same rate as those treated with BM, using the ligated loop technique in vivo. There was a similar significant inhibition of Ca absorption in both BM-treated and diet-restricted chicks in both duodenum (to 73% and 67% of the control level, respectively) and jejunum (to 74% and 77% of the control level, respectively). Absorption of Ca from the ileum of BM-treated birds equaled that in controls, but diet-restricted chicks unexpectedly showed a 100% stimulation. We conclude that in the chick, BM treatment does not stimulate ileal calcium absorption, but diet-restriction does. The lack of effect of bM in the ileum may reduce the magnitude of the decrease in Ca absorption from the entire small intestine when compared to the duodenum and jejunum alone, but the stimulated absorption seen in the ileum of diet- restricted birds is almost sufficient to restore Ca absorption from the entire small intestine to the control level.