Cestrum diurnum intoxication in normal and hyperparathyroid pigs.

The effect of ingestion of dried leaves of Cestrum diurnum, a plant shown to contain a 1,25-dihydroxycholecalciferol-like principle, was tested in normal pigs fed 1.2% calcium and 1.0% phosphorus for 10 weeks from weaning and in hyperparathyroid pigs fed 0.8% calcium and 1.6% phosphorus for the same periods of time. Addition of 3% Cestrum diurnum leaf meal rapidly resulted in decreased feed consumption and weight gain, hypercalcemia and hypophosphatasemia. In normal pigs, plasma calcium rose to 16 mg/100 ml within one week and remained high for the 4 week experimental period. In hyperparathyroid pigs with hypocalcemia, plasma calcium rose to 12.75 mg/100 ml within one week and later approached 15 mg/100 ml. Ingestion of Cestrum diurnum retarded cell differentiation of growth cartilages. Arrested osteocytic osteolysis was observed within one week with osteopetrosis of epiphyses and metaphyses. The negative effect on the resorbing osteocytes then caused osteonecrosis which, in combination with lack of bone formation because of atrophy of osteoblasts, resulted in osteopenia within 4 weeks. Dystrophic calcinosis occurred within 2 weeks and was widespread after 4 weeks in lungs, kidneys, heart and vessels. Atrophy of parathyroid cells was severe after one week. Hyperparathyroid pigs responded with skeletal lesions, dystrophic calcinosis and parathyroid atrophy more rapidly and severely than normal pigs. The biochemical and anatomical changes in Cestrum diurnum ingestion are closely similar to those in vitamin D3 intoxication in pigs. Whereas pigs can tolerate large amounts of vitamin D3 because of feed-back control of 1 alpha-hydroxylation in the kidney, this control point is by-passed in Cestrum diurnum ingestion and intoxication occurs promptly.