Toxic effects of Solanum malacoxylon on sheep bone.

Solanum malacoxylon (Sm), a calcinogenic plant that contains 1,25-(OH)2D3 glycoside, was administered orally to sheep. Fifty milligrams of air-dried leaves three times a week caused an increased volume density of cancellous bone within lumbar vertebrae and an increased trabecular thickness. There was little remodeling activity at the end of a 180-day treatment period, and few trabecular bone surfaces had tetracycline double labels at this time. Bone biopsies taken at the end of a 1-month treatment demonstrated increased extent of bone-forming surfaces and osteoid volume. Sm caused a mineralization defect that was transitory but resulted in unmineralized lines and foci in osteones. These remaining foci of unmineralized bone were associated with the deposition of acid mucopolysaccharide, and acid mucopolysaccharide accumulation could be identified on all bone envelopes in 30-day biopsy specimens. A similar hyperostosis in the metaphyses of rats was produced by parenteral administration of 1,25-(OH)2D3 for 10 days.