AJP - Endocrinology and Metabolism, Vol 254, Issue 4 E496-E504, Copyright © 1988 by American Physiological Society
Diabetes and low Ca-P diet have opposite effects on adult and fetal bone mineral metabolism
J. Verhaeghe, R. Bouillon, W. Lissens, W. J. Visser and F. A. Van Assche
Department of Obstetrics and Gynecology, Katholieke Universiteit Leuven, Belgium.
The effect of diabetes on maternal bone mineral metabolism and fetal
mineralization was studied in nonpregnant and pregnant BB rats fed two
diets (0.85% calcium-0.7% phosphorus and 0.2% calcium-phosphorus).
Non-pregnant female diabetic rats had normal total bone mineral content
(BMC), despite decreased trabecular bone volume density (TBVD). Nondiabetic
rats on the low calcium-phosphorus diet showed decreased TBVD, signs of
increased bone turnover, and decreased BMC; plasma 1,25-dihydroxyvitamin D3
[1,25 (OH)2D3] was increased and urinary calcium excretion was decreased. A
similar response was observed in diabetic rats with a further decrease in
TBVD. Nondiabetic 21-day pregnant rats on high and low calcium-phosphorus
diets had higher 1,25(OH)2D3 than nonpregnant rats (98 vs. 58 and 328 vs.
147 pg/ml, respectively). Maternal BMC did not change during pregnancy but
was decreased by the low calcium-phosphorus diet; fetal mineral content was
not influenced by the low calcium-phosphorus regime. No increase in
1,25(OH)2D3 was observed in pregnant diabetic rats (57 vs. 52 and 112 vs.
128 pg/ml in high and low calcium-phosphorus diet groups). Fetal
mineralization was severely impaired in diabetes but was not further
decreased by the low calcium-phosphorus diet. Thus nonpregnant diabetic
rats respond normally to a low calcium-phosphorus diet, but pregnant
diabetic rats do not show increased 1,25(OH)2D3 levels due to impairment of
fetal mineralization.
