Effects of Low Calcium and Low Phosphorus Diets on the Duodenal Absorption of Calcium in Betamethasone-Treated Chicks

Abstract

The effect of oral administration of betamethasone (25 microgram kg-1 day-1) on the duodenal absorption of calcium has been studied in chicks using the ligated loop technique in vivo. The chicks were fed normal calcium, normal phosphorus (NCaNP), low calcium, normal phosphorus (LCaNP) or normal calcium, low phosphorus (NCaLP) diets. Daily oral administration of betamethasone for 2-3 weeks markedly reduced the absorption of calcium in chicks fed the NCaNP diet, but did not significantly affect the adaptation in absorption when the NCaLP or LCaNP diets were fed for the same period of time. In one group of chicks, betamethasone was administered daily for 10 days before the birds were transferred to the NCaLP or LCaNP diets. Adaptation was again unaffected by betamethasone treatment. Administration of betamethasone caused a marked retardation in growth-rate, hypercalcaemia and an increased percentage of ash in the tibiae.

Effect of low calcium and low phosphorus diets on the intestinal absorption of water in intact and parathyroidectomized pigs

“…It is possible that low plasma phosphate concentration could stimulate adrenal function which would lead to increased absorption. The fact that both glucocorticoids and the feeding of low P diets cause reduced growth rate in young animals [13] is suggestive, but weak, evidence for this possibility. We have shown that the oral administration of glucocorticoids does not affect the adaptation in Ca absorption to low Ca and low P diets [13].…”

“…The fact that both glucocorticoids and the feeding of low P diets cause reduced growth rate in young animals [13] is suggestive, but weak, evidence for this possibility. We have shown that the oral administration of glucocorticoids does not affect the adaptation in Ca absorption to low Ca and low P diets [13]. However, we are not aware of any evidence to support an effect of low plasma phosphate concentrations on adrenal function.…”

REVERSAL OF BETAMETHASONE-INDUCED INHIBITION OF INTESTINAL CALCIUM ABSORPTION BY 1α-Hydroxycholecalciferol

“…The increase in the concentration of calcium and the decrease in the concentration of phosphate in the plasma of pigs (and also in chicks, Fox, Care & Blahos, 1978a) treated with betamethasone alone deserves comment. These changes suggest hypersécrétion of para¬ thyroid hormone (PTH) and indeed Au (1976) demonstrated a stimulation of secretion of PTH from bovine parathyroid glands in organ culture as a result of the addition of cortisol to the culture medium.…”

The Time Sequence of Adaptive Changes to Dietary Phosphorus Deficiency in the Chick

“…Studies of long term (1-3 weeks) dietary phosphorus (P) depletion have established that adaptive changes occur which are similar to those seen in calcium (Ca) depletion. In the chick there is a marked rise in the intestinal rate of absorption of Ca and P (Morrisey and Wasserman 1971;Fox and Care 1978) which is accompanied by a rise in 25hydroxycholecalciferol-1-hydroxylase (1-hydroxylase) activity (only at P concentrations below 0.25%) and a marked increase in the accumulation of 1,25-dihydroxycholecalciferol (1,25 (OH) 2 D 3 ) in the intestinal mucosa (Sommerville, Swaminathan and Care 1978). Similar rises in intestinal Ca absorption and l,25(OH) 2 D 3 accumulation have been reported in the rat (Tanaka, Frank and DeLuca 1973) and 1-hydroxylase activity in the pig (Sommerville, Fox, Care and Swaminathan 1978) in response to dietary P deficiency.…”