Solanum glaucophyllum (Sg) (synonym S. malacoxylon) is a plant toxic to cattle due to its high levels of 1,25-dihydroxyvitamin D3 as glycoside derivatives. Sg causes a disease characterized by wasting and calcification of soft tissues. The effects of vitamin D are not only important in calcium homeostasis, but also in immune regulation, cell growth and cell differentiation. Skin samples in Sg-intoxicated and control heifers were studied histologically. Cellular differentiation and proliferation were analysed by immunohistochemical expression of cytokeratins, involucrin and proliferating cell nuclear antigen (PCNA). The results were obtained by image processing and analysis and were statistically evaluated. Sg-intoxicated cattle showed atrophy of epidermis and severe involution of hair follicles and of sebaceous and sweat glands. As judged by PCNA expression, cellular proliferation was reduced, even though the reduction was not statistically significant. The analysed markers of differentiation, e.g. involucrin and cytokeratins 10 and 11, changed in relation to Sg-poisoning. The possible pathogenesis of the skin lesions is discussed.

The effects of plant-induced hypervitaminosis D on cell differentiation in the skin, aorta and lung of ruminants were studied. Skin and aorta tissue samples from experimentally Solanum glaucophyllum (Sg)-intoxicated cows were obtained and analysed. Also, aortas and lungs of sheep with spontaneous enzootic calcinosis (EC) induced by Nierembergia veitchii (Nv), and the same organs of rabbits intoxicated with Sg, were analysed by electron microscopy and immunohistochemical techniques. Sg-poisoned heifers showed a highly significant decrease in epidermal thickness due to a reduction in cell layers; also, a qualitative and quantitative atrophy of sebaceous and sweat glands was observed. Sg intoxication affected the proliferation of keratinocytes. The main ultrastructural alterations observed in aorta and lung of EC affected sheep and rabbits were a modification in smooth muscle cells (SMCs) and the activation of fibroblasts in the interstitium. Some macrophages and multinucleated giant cells, with calcium crystals in the cytoplasm, were found in areas of increased matrix in these tissues. A decrease in the amount of elastic fibres as a function of the intoxication time was observed. This reduction was significant after 15 days of intoxication.

The aim of this study was to describe the bone changes observed after a daily oral administration of the calcinogenic plant Solanum malacoxylon (syn. S. glaucophyllum) (Sm) during 9 days. The Sm-poisoned rabbits had an increase of bone resorption in the endosteal surface of the cortical zone and also in the surface covered by osteoblasts of the primary and secondary spongiosa of the trabecular bone compartment. Moreover, the epiphyseal growth plates in long bones appeared narrower than in the control rabbits, with reduction of the proliferative and hyperthrophic chondrocyte zones. The electron microscopic study revealed a significant decrease of proteoglycans in the hyperthrophic chondrocyte zone evidenced by a significant reduction of rutenium red positive granules in the poisoned rabbit. Altogether, these data suggest that cell differentiation may play a pivotal role in the pathogenesis of Sm-induced bone lesions