Influence of Nutritional Factors on Skeletal Atrophy from Disuse and on Normal Bones of Mature Rats

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Abstract
The effects of certain dietary alterations and of injections of sesame oil and estradiol dipropionate on the composition of the humeri of normal and denervated limbs of mature rats have been determined. Severe calcium or phosphorus deficiencies caused a reduction in percentage of ash and in amount of bone in the humeri of the normal limbs. Both types of mineral deficiencies accentuated the atrophic process occurring in the humeri of the paralyzed limbs. These deleterious effects on bone were more marked in the case of calcium deprivation than in lack of phosphorus. An increase of the calcium content of an adequate diet by 43% resulted in an increase of the ash content of the humeri of both limbs but produced no other significant effects on the bones. An increase of the phosphorus content of an adequate diet by 23% had no demonstrable effects on the bones of either limb. Severe restriction of the daily intake of an adequate diet resulted in an atrophy of the humeri of the normal limbs and in an increase of the disuse atrophy of the paralyzed limbs. These deleterious effects were increased in animals receiving the same daily intake of minerals in a diet with a very low protein content. Evidence was obtained indicating that the injections of sesame oil had a deleterious effect on the humeri of normal limbs and accentuated the atrophy of the humeri of the paralyzed limbs. The administration of estradiol dipropionate in a dosage of 2.5 µg on alternate days was found to decrease the atrophy of the humeri of the normal limbs caused by the combination of seseame oil injections and food restriction, and to decrease the atrophy of the humeri of the paralyzed limbs.