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BONE STRENGTH AND CALCIUM RETENTION OF RATS IN HYPERVITAMINOSIS‐A
Author(s) -
Khogali A.
Publication year - 1966
Publication title -
quarterly journal of experimental physiology and cognate medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0033-5541
DOI - 10.1113/expphysiol.1966.sp001832
Subject(s) - hypervitaminosis a , triiodothyronine , endocrinology , medicine , hormone , thyroid , calcium , hypervitaminosis , vitamin , atrophy , retinol
Newly‐weaned male albino rats were fed by gavage excessive doses of vitamin A for 4 weeks either alone or with one of the thyroid hormones: L‐triiodothyronine and D‐triiodothyronine. Some rats were given the thyroid hormones alone. It was found that: 1. The rats fed 6000 i.u. and 12,000 i.u. vitamin A per day gained weight normally and did not sustain spontaneous fractures. 2. A dose of 24,000 i.u. vitamin A per day retarded the growth of the rats and spontaneous fractures of the long bones (mainly tibiæ) occurred. 3. The bones of the animals suffering from hypervitaminosis‐A were abnormally thin and their bending moment at breaking was significantly reduced. The breaking stress (quality) of the bones was also reduced but this can be explained by a change in texture of the bones and is not due to altered quality of the bony material. The stiffness (E) of the bones was not affected. 4. The percentage mineral content of the bones from hypervitaminotic rats was normal, but the total calcium retention of the animals was reduced. 5. L‐triiodothyronine and D‐triiodothyronine in doses of 5 µg. per day aggravated the skeletal changes in hypervitaminosis‐A. 6. The thyroid hormones alone did not produce any significant changes in the physical properties of the femora of rats. It is suggested that, in hypervitaminosis‐A, the quantity and distribution of the bony material is disturbed but its quality is probably unaltered.