Effect of the addition of different concentrations of Solanum glaucophyllum desf. extract on chondrocyte cultures from the growth cartilage of newborn rats.

Solanum glaucophyllum Desf. is a calcinogenic plant responsible for enzootic calcinosis that affects ruminants and causes alterations in bone and cartilaginous tissues, among others. It is believed that changes in cartilage tissue, with reduced bone growth, are due to hypercalcitoninism, caused by excess vitamin D. However, we hypothesized that S. glaucophyllum Desf. can act directly on chondrocytes and therefore, chondrocyte cultures from the epiphysis of the long bones of newborn rats were used as a model to elucidate the direct effects of S. glaucophyllum Desf. on bone growth. Plant samples were collected from Cañuelas, Argentina. An aliquot of the plant extract was used to quantify vitamin D (1,25(OH)2D3). The effects of the three concentrations of the plant extract were tested in cultures of chondrocytes extracted from the epiphyses of the long bones of 32 three-day-old Wistar rats. A control group (without extract), and three groups treated with different concentrations of plant extract were formed: group 1 (100 µL/L); group 2 (1 mL/L), and group 3 (5 mL/L), containing respectively 1 × 10-9 M, 1 × 10-8 M, and 5 × 10-8 M of 1,25(OH)2D3. After 7, 14, and 21 days of culture, MTT assay for cell viability, alkaline phosphatase activity, and quantification of the percentage of areas with glycosaminoglycans (GAG) stained with periodic acid-Schiff (PAS) were performed. On day 7, all chondrocytes in group 3, that is, those with the highest concentration of plant extract, died. On days 14 and 21, groups 1 and 2 showed a significant reduction in chondrocyte viability compared to the control. At 7, 14, and 21 days, groups 1 and 2 showed significantly lower alkaline phosphatase activity than the control. On day 21, group 2 showed a significant reduction in areas with PAS + GAGs. There were no significant differences between the groups in the expression of gene transcripts for Sox9, Col2, ColX, and aggrecan. The S. glaucophyllum Desf. extract directly affected growing rat chondrocytes by reducing viability, alkaline phosphatase activity, and GAG synthesis without altering the expression of gene transcripts for Sox9, Col2, ColX, and aggrecan, which may be one of the mechanisms by which there is a reduction in bone growth in animals intoxicated by the plant.

Bone traits and gastrointestinal tract parameters of piglets fed cholecalciferol and 1, 25-dihydroxycholecalciferol glycoside

The objective of this study was to evaluate the cholecalciferol and 1,25-dihydroxycholecalciferol glycoside supplementation in piglet diet on organ biometry and physicochemical composition, pH of the digestive tract contents, and bone traits. A total of 128 entire male piglets (21 days-old, 6.82±0.38 kg body weight) were distributed in a completely randomized block design with eight replications and four animals per experimental unit. The treatments were composed of a diet 100/0 = 100% of the vitamin D supplemented with cholecalciferol; 50/50 = 50% supplemented with cholecalciferol + 0.25 µg of 1,25(OH)2 D3 glycoside; 25/75 = 25% supplemented with cholecalciferol + 0.375 µg of 1,25(OH)2 D3 glycoside; and 0/100 = 0.50 µg of 1,25(OH)2 D3 glycoside. The results indicated that piglets fed 100/0 showed an increase in spleen weight compared with those fed 0/100 and greater heart dry matter than piglets fed the 50/50 diet. Phosphorus concentration in the spleen was higher in piglets that received 25/75 when compared with those that received the 100/0 and 0/100 diets. Piglets that received the 0/100 diet showed higher pH of the stomach contents, but showed reduced pH of the contents of the jejunum and ileum. The width of the epiphysis and diaphysis was greater when piglets consumed the 50/50 treatment; however, a lower epiphysis height was observed. The use of 1,25(OH)2 D3 glycoside alone in piglet diets does not negatively influence the pH of the gastrointestinal tract and organ physicochemical composition. In addition, the use of diets with 1,25(OH)2 D3 glycoside as a replacement for cholecalciferol reduces spleen weight and promotes improvements in bone development.

Substituição de vit D3 pelo metabólito de origem vegetal 1, 25(OH)2D3 influenciando o desempenho e qualidade óssea em frangos de corte aos 21 dias / Replacement of vitamin D3 with 1.25(OH)2D3 metabolite of plant origin influences performance and bone quality in broilers at 21 days of age

Objetivou-se avaliar a inclusão do metabólito 1,25(OH)2D3 como fonte de substituição da vitamina D3 (colecalciferol) no suplemento vitamínico das rações de frangos de corte, assim como a influência desse metabólito sobre o desempenho e qualidade óssea até os 21 dias de idade. Foram alojados 1400 pintos de corte machos, aos 7 dias de alojamento, esses foram pesados e divididos em seis tratamentos experimentais, com 6 repetições e 38 aves por repetição. Os tratamentos constituíam da manutenção da quantidade de vitamina D3para frangos de corte em: 100%, 75%, 50%, 25% e 0%, e adição do metabolito vitamínico bioativo [1,25(OH)2D3] em quantidade fixa, mais o tratamento controle, que recebeu somente a vitamina D3 na dose recomendada como única fonte de vitamina D. Os dados foram submetidos à análise de variância usando o procedimento General Linear Models do software SAS® e, em caso de diferenças estatisticamente significativas, as médias foram comparadas pelo teste de Dunnett a 5% de probabilidade. O peso médio, o ganho de peso e o ganho de peso diário diferiram significativamente (p<0,05) do controle, pelo teste de Dunnett, somente nos tratamentos em que houve inclusão de 75% Vit D3 +1,25(OH)2D3, sendo observado melhores médias para essas variáveis. O consumo de ração foi maior (p<0,05) nos frangos que receberam 25% Vit D3+1,25(OH)2D3, quando comparado com as aves que receberam a dieta controle. Quando se incluiu o 1,25(OH)2D3 como fonte única da vitamina D3, foram observados os piores valores (p<0,05) para peso médio, ganho de peso, ganho de peso diário e consumo, não havendo diferença significativa (p>0,05) para a conversão alimentar. A morfometria óssea não foi influenciado (p>0,05) pela redução da vitamina D3 no suplemento vitamínico e nem pela utilização do 1,25(OH)2D3. O percentual de cálcio nas cinzas das tíbias nos tratamentos em que houve inclusão de 75% Vit D3+1,25(OH)2D3 foi superior (p<0,05)...(AU)

The objective of this study was to evaluate the inclusion of 1.25(OH)2D3 as a substitute of vitamin D3 (cholecalciferol) in the vitamin supplement of broiler diets, as well as the influence of this metabolite on performance and bone quality up to 21 days of age. A total of 1,400 male chicks were used. At 7 days of age, the animals were weighed and divided into six experimental treatments, with 6 replicates and 38 birds per replicate. The treatments consisted of maintaining the amount of vitamin D3 for broilers at 100%, 75%, 50%, 25% and 0% plus the addition of a fixed quantity of bioactive vitamin metabolite [1.25(OH)2D3]. As the control treatment, the animals received only vitamin D3 at the recommended dose as the sole source of vitamin D. Data were submitted to analysis of variance using the General Linear Models procedure of the SAS® software. In the case of statistically significant differences, means were compared by the Dunnett test at 5% probability. The mean weight, weight gain and daily weight gain differed significantly (p<0.05) from the control by the Dunnett test only for the treatment with inclusion of 75% vitamin D3+1.25 (OH)2D3, with better averages for these variables. Feed intake was higher (p<0.05) in chickens receiving 25% vitamin D3+1.25(OH)2D3 when compared to birds fed the control diet. The worst (p<0.05) mean weight, weight gain, daily weight gain and feed intake were observed when 1.25(OH)2D3 was included as a single source of vitamin D3, with no significant difference (p>0.05) in feed conversion. Bone morphometry was not influenced (p>0.05) by the reduction of vitamin D3 in the vitamin supplement nor by the use of 1.25(OH)2D3. The calcium percentage in tibia ashes was higher (p<0.05) for the treatment with 75% vitamin D3+1.25(OH)2D3 inclusion compared to control by the Dunnett test. The reduction of vitamin D3 up to...(AU)

Substituição de vit D3 pelo metabólito de origem vegetal 1, 25(OH)2D3 influenciando o desempenho e qualidade óssea em frangos de corte aos 21 dias / Replacement of vitamin D3 with 1.25(OH)2D3 metabolite of plant origin influences performance and bone quality in broilers at 21 days of age

Objetivou-se avaliar a inclusão do metabólito 1,25(OH)2D3 como fonte de substituição da vitamina D3 (colecalciferol) no suplemento vitamínico das rações de frangos de corte, assim como a influência desse metabólito sobre o desempenho e qualidade óssea até os 21 dias de idade. Foram alojados 1400 pintos de corte machos, aos 7 dias de alojamento, esses foram pesados e divididos em seis tratamentos experimentais, com 6 repetições e 38 aves por repetição. Os tratamentos constituíam da manutenção da quantidade de vitamina D3para frangos de corte em: 100%, 75%, 50%, 25% e 0%, e adição do metabolito vitamínico bioativo [1,25(OH)2D3] em quantidade fixa, mais o tratamento controle, que recebeu somente a vitamina D3 na dose recomendada como única fonte de vitamina D. Os dados foram submetidos à análise de variância usando o procedimento General Linear Models do software SAS® e, em caso de diferenças estatisticamente significativas, as médias foram comparadas pelo teste de Dunnett a 5% de probabilidade. O peso médio, o ganho de peso e o ganho de peso diário diferiram significativamente (p0,05) para a conversão alimentar. A morfometria óssea não foi influenciado (p>0,05) pela redução da vitamina D3 no suplemento vitamínico e nem pela utilização do 1,25(OH)2D3. O percentual de cálcio nas cinzas das tíbias nos tratamentos em que houve inclusão de 75% Vit D3+1,25(OH)2D3 foi superior (p<0,05)...

The objective of this study was to evaluate the inclusion of 1.25(OH)2D3 as a substitute of vitamin D3 (cholecalciferol) in the vitamin supplement of broiler diets, as well as the influence of this metabolite on performance and bone quality up to 21 days of age. A total of 1,400 male chicks were used. At 7 days of age, the animals were weighed and divided into six experimental treatments, with 6 replicates and 38 birds per replicate. The treatments consisted of maintaining the amount of vitamin D3 for broilers at 100%, 75%, 50%, 25% and 0% plus the addition of a fixed quantity of bioactive vitamin metabolite [1.25(OH)2D3]. As the control treatment, the animals received only vitamin D3 at the recommended dose as the sole source of vitamin D. Data were submitted to analysis of variance using the General Linear Models procedure of the SAS® software. In the case of statistically significant differences, means were compared by the Dunnett test at 5% probability. The mean weight, weight gain and daily weight gain differed significantly (p0.05) in feed conversion. Bone morphometry was not influenced (p>0.05) by the reduction of vitamin D3 in the vitamin supplement nor by the use of 1.25(OH)2D3. The calcium percentage in tibia ashes was higher (p<0.05) for the treatment with 75% vitamin D3+1.25(OH)2D3 inclusion compared to control by the Dunnett test. The reduction of vitamin D3 up to...

Enzootic calcinosis in horses grazing Solanum glaucophyllum in Argentina.

Solanum glaucophyllum, a toxic plant known for its calcinogenic effects, causes enzootic calcinosis in ruminant and monogastric animals. We describe an outbreak of enzootic calcinosis that occurred in a herd of 110 horses grazing pastureland heavily contaminated with S. glaucophyllum in Buenos Aires province, Argentina. Ten horses developed clinical signs, and 6 horses died. Clinical signs included abnormal gait (stiff-legged action, short strides), stiffness, thoracolumbar kyphosis, reluctance to move, wide stance, chronic weight loss, weakness, recumbency, and difficulty standing. Autopsy of 2 horses revealed severe mineralization of the aorta, pulmonary arteries, heart, and lungs, consistent with enzootic calcinosis. Although horses usually have very selective grazing behavior, under food restriction conditions, they can ingest the toxic plants and can develop the disease. Enzootic calcinosis should be considered as a differential diagnosis in horses grazing S. glaucophyllum-invaded pasturelands with compatible clinical signs and lesions.

Effects of 1, 25-dihydroxycholecalciferol and reduced vitamin D3 level on broiler performance and bone quality

This study was conducted to evaluate the effect of two levels of vitamin D3 with or without 1,25- dihydroxycholecalciferol (1,25(OH)2D3) on live performance and bone quality of broiler chickens. For that, we used a completely randomized design in a 2 × 2 factorial arrangement, with eight replicates of 30 Cobb®500 male broiler chicks each (n = 960). The two levels of vitamin D3 and the addition or not of 0.5 µg 1,25(OH)2D3/kg were considered as main factors. The vitamin D3 levels were: 2500/2000 IU/kg and 1250/1000 IU/kg for the starter (1 to 21 days) and grower (22 to 40 days) phases, respectively, with the first representing the levels used in industry (100%) and the second, a reduction in 50% of those levels. The 1,25(OH)2D3 source was Solanum glaucophyllum. On days 21 and 40, one broiler per replicate was killed and long bones were removed for analyses of mineral percentage, bone mineral density, biomechanical properties, and morphology. No significant differences were found related to vitamin D3 levels and the addition or not of 1,25(OH)2D3 for live performance, mineral percentage, strength, stiffness, and morphology. Toughness was lower when 1,25(OH)2D3 was used at 21 days, but this effect was not observed at 40 days of age. Bone mineral density was greater when 100% of vitamin D3 was used at 40 days of age. The reduction of up to 50% of vitamin D3 levels is sufficient to ensure performance and bone development of broilers at 21 and 40 days of age. The inclusion of 0.5 µg 1,25(OH)2D3/kg in addition to diets with sufficient levels of vitamin D3 shows no effect on the improvement of those parameters at the same ages.(AU)

1, 25-dihidroxivitamina-D 3 sobre as características ósseas de frangos de corte fêmeas / 1, 25-dihydroxyvitamin-D3 over bony characteristics of female broilers

Objetivou-se avaliar as características dos tibiotarsos de frangos de corte fêmeas. As variáveis analisadas foram os pesos in natura, secos e desengordurados, o comprimento, os diâmetros, a resistência óssea, o índice de Seedor (IS), os percentuais de proteínas colagenosas (PC), as proteínas não colagenosas (PNC), os minerais (cálcio, fósforo, potássio e sódio) e as cinzas. Foram utilizadas 648 aves, da marca comercial Cobb®, em um delineamento em blocos ao acaso, com seis tratamentos e seis repetições, com 18 aves por unidade experimental. Os tratamentos consistiram na suplementação de 0,00; 0,50; 1,00; 1,50; 2,00 e 2,50 µg de 1,25-dihidroxivitamina-D3 (1,25(OH)2D3)/kg de ração. Aos 21 e 35 dias de idade, as aves foram pesadas e uma ave por unidade experimental (UE) com o peso médio da UE foi eutanasiada para a obtenção dos tibiotarsos e subsequente análise dos parâmetros ósseos. As variáveis métricas, bem como a composição orgânica (PC), a densidade (IS) e a resistência à quebra dos ossos das aves, não foram influenciadas pelos tratamentos. No recebimento de 2,50 µg de 1,25(OH)2D3/kg de ração, observou-se maior retenção mineral (cinzas) nos ossos das aves aos 35 dias de idade.(AU)

This study aimed to evaluate the characteristics of tibiotarsus of female broilers. The variables analyzed were the weights in natura, dry and degreased, length, diameter, bone strength, Seedor index, percentage of collagenous protein (CP), non-collagenous proteins (NCP), minerals (calcium, phosphorus, potassium and sodium), and ash. Six hundred forty-eight, Cobb® birds were used, a design of randomized blocks with six treatments and six replicates of 18 birds each. The treatments consisted of supplementation of 0.00; 0.50; 1.00; 1.50; 2.00 to 2.50 µg of 1,25-dihydroxyvitamin-D3 (1,25(OH)2D3)/kg of ration. At 21 and 35 days of age the birds were weighed and a unit/experimental unit (EU) with the EU average weight was euthanized to obtain the tibiotarsos and subsequent analysis of the bone parameters. The metric variables, as well as the organic composition (CP), density (IS) and resistance to breakage of the bones of the birds were not affected by treatments. Upon reception of 2.50 µg of 1,25(OH)2D3/kg ration, there was a higher mineral retention (ashes) in the bones of female broilers at 35 days of age.(AU)

1, 25-dihidroxivitamina-D 3 sobre as características ósseas de frangos de corte fêmeas / 1, 25-dihydroxyvitamin-D3 over bony characteristics of female broilers

Objetivou-se avaliar as características dos tibiotarsos de frangos de corte fêmeas. As variáveis analisadas foram os pesos in natura, secos e desengordurados, o comprimento, os diâmetros, a resistência óssea, o índice de Seedor (IS), os percentuais de proteínas colagenosas (PC), as proteínas não colagenosas (PNC), os minerais (cálcio, fósforo, potássio e sódio) e as cinzas. Foram utilizadas 648 aves, da marca comercial Cobb®, em um delineamento em blocos ao acaso, com seis tratamentos e seis repetições, com 18 aves por unidade experimental. Os tratamentos consistiram na suplementação de 0,00; 0,50; 1,00; 1,50; 2,00 e 2,50 µg de 1,25-dihidroxivitamina-D3 (1,25(OH)2D3)/kg de ração. Aos 21 e 35 dias de idade, as aves foram pesadas e uma ave por unidade experimental (UE) com o peso médio da UE foi eutanasiada para a obtenção dos tibiotarsos e subsequente análise dos parâmetros ósseos. As variáveis métricas, bem como a composição orgânica (PC), a densidade (IS) e a resistência à quebra dos ossos das aves, não foram influenciadas pelos tratamentos. No recebimento de 2,50 µg de 1,25(OH)2D3/kg de ração, observou-se maior retenção mineral (cinzas) nos ossos das aves aos 35 dias de idade.(AU)

This study aimed to evaluate the characteristics of tibiotarsus of female broilers. The variables analyzed were the weights in natura, dry and degreased, length, diameter, bone strength, Seedor index, percentage of collagenous protein (CP), non-collagenous proteins (NCP), minerals (calcium, phosphorus, potassium and sodium), and ash. Six hundred forty-eight, Cobb® birds were used, a design of randomized blocks with six treatments and six replicates of 18 birds each. The treatments consisted of supplementation of 0.00; 0.50; 1.00; 1.50; 2.00 to 2.50 µg of 1,25-dihydroxyvitamin-D3 (1,25(OH)2D3)/kg of ration. At 21 and 35 days of age the birds were weighed and a unit/experimental unit (EU) with the EU average weight was euthanized to obtain the tibiotarsos and subsequent analysis of the bone parameters. The metric variables, as well as the organic composition (CP), density (IS) and resistance to breakage of the bones of the birds were not affected by treatments. Upon reception of 2.50 µg of 1,25(OH)2D3/kg ration, there was a higher mineral retention (ashes) in the bones of female broilers at 35 days of age.(AU)

Intoxicação natural por Solanum glaucophyllum (Solanaceae) em búfalos no Pantanal Matogrossense / Natural poisoning by Solanum glaucophyllum(Solanaceae) in buffaloes in the Brazilian Pantanal

Descreve-se a ocorrência de calcinose enzoótica em búfalos no município de Poconé, Mato Grosso, associado ao consumo de Solanum glaucophyllum (Sg) [=Solanum malacoxylon]. Os casos foram observados entre os anos de 2007 e 2009. Em um rebanho de 40 búfalos, cinco apresentaram emagrecimento progressivo, dorso arqueado, marcha rígida, por vezes com dificuldade para se levantar e locomover, permanecendo apoiando sobre os carpos.Três animais recuperaram-se parcialmente e dois foram eutanasiados in extremis. Os principais achados de necropsia foram calcificação de tecidos moles, principalmente em artérias de grande e médio calibres. A presença de S. glaucophyllum nas pastagens, os sinais clínicos, além dos achados ultrassonográficos e patológicos envolvendo múltiplas calcificações de tendões e outros tecidos, são compatíveis com intoxicação por Solanum glaucophyllum.(AU)

This report describes the occurrence of enzootic calcinosis in buffaloes in the municipality of Pocone, Mato Grosso, due to the consumption of Solanum glaucophyllum (Sg) [=Solanum malacoxylon]. The cases were observed in the years 2007 and 2009. In a herd of 40 buffaloes, five showed weight loss, arched back, stiff gait, sometimes difficulty to raise and walk, and leaning on the carpus. Three buffaloes recovered partially and two were euthanized in extremis. The main necropsy findings were calcification of soft tissues, especially of large and medium arteries. The presence of S. glaucophyllum in the pasture, clinical signs, in addition to the sonographic and pathologic calcification involving tendons and other tissues, are consistent with Solanum glaucophyllum poisoning.(AU)

Intoxicação natural por Solanum glaucophyllum (Solanaceae) em búfalos no Pantanal Matogrossense / Natural poisoning by Solanum glaucophyllum(Solanaceae) in buffaloes in the Brazilian Pantanal

Descreve-se a ocorrência de calcinose enzoótica em búfalos no município de Poconé, Mato Grosso, associado ao consumo de Solanum glaucophyllum (Sg) [=Solanum malacoxylon]. Os casos foram observados entre os anos de 2007 e 2009. Em um rebanho de 40 búfalos, cinco apresentaram emagrecimento progressivo, dorso arqueado, marcha rígida, por vezes com dificuldade para se levantar e locomover, permanecendo apoiando sobre os carpos.Três animais recuperaram-se parcialmente e dois foram eutanasiados in extremis. Os principais achados de necropsia foram calcificação de tecidos moles, principalmente em artérias de grande e médio calibres. A presença de S. glaucophyllum nas pastagens, os sinais clínicos, além dos achados ultrassonográficos e patológicos envolvendo múltiplas calcificações de tendões e outros tecidos, são compatíveis com intoxicação por Solanum glaucophyllum.

This report describes the occurrence of enzootic calcinosis in buffaloes in the municipality of Pocone, Mato Grosso, due to the consumption of Solanum glaucophyllum (Sg) [=Solanum malacoxylon]. The cases were observed in the years 2007 and 2009. In a herd of 40 buffaloes, five showed weight loss, arched back, stiff gait, sometimes difficulty to raise and walk, and leaning on the carpus. Three buffaloes recovered partially and two were euthanized in extremis. The main necropsy findings were calcification of soft tissues, especially of large and medium arteries. The presence of S. glaucophyllum in the pasture, clinical signs, in addition to the sonographic and pathologic calcification involving tendons and other tissues, are consistent with Solanum glaucophyllum poisoning.

Thymic atrophy in cattle poisoned with Solanum glaucophyllum / Atrofia do timo em bovinos intoxicados por Solanum glaucophyllum

Solanum glaucophyllum (Sg) [= S. malacoxylon] is a calcinogenic plant inducing "Enzootic Calcinosis" in cattle. The 1,25-dihydroxyvitamin D3, its main toxic principle, regulates bone and calcium metabolism and also exerts immunomodulatory effects. Thymocyte precursors from bone marrow-derived progenitor cells differentiate into mature T-cells. Differentiation of most T lymphocytes is characterized not only by the variable expression of CD4/CD8 receptor molecules and increased surface density of the T cell antigen receptor, but also by changes in the glycosylation pattern of cell surface glycolipids or glycoproteins. Thymocytes exert a feedback influence on thymic non-lymphoid cells. Sg-induced modifications on cattle thymus T-lymphocytes and on non-lymphoid cells were analysed. Heifers were divided into 5 groups (control, intoxicated with Sg during 15, 30 or 60 days, and probably recovered group). Histochemical, immunohistochemical, lectinhistochemical and morphometric techniques were used to characterize different cell populations of the experimental heifers. Sg-poisoned heifers showed a progressive cortical atrophy that was characterized using the peanut agglutinin (PNA) lectin that recognizes immature thymocytes. These animals also increased the amount of non-lymphoid cells per unit area detected with the Picrosirius technique, WGA and DBA lectins, and pancytokeratin and S-100 antibodies. The thymus atrophy found in intoxicated animals resembled that of the physiological aging process. A reversal effect on these changes was observed after suppression of the intoxication. These findings suggest that Sg-intoxication induces either directly, through the 1,25-dihydroxyvitamin D3 itself, or indirectly through the hypercalcemia, the observed alteration of the thymus.

Solanum glaucophyllum (Sg) [= S. malacoxylon] é uma planta calcinogênica que induz "Calcinose Enzoótica" em bovinos. O 1,25-dihidroxivitamina D3, seu principal agente tóxico, regula o metabolismo ósseo, o metabolismo de cálcio e também mostra efeitos na imunomodulação. Precursores de timócitos derivados da medula óssea se diferenciam em linfócitos T maduros. A diferenciação da maioria dos linfócitos T é caracterizada pela expressão variável de moléculas de receptores CD4/CD8 e densidade aumentada dos receptores antigênicos de superfície de células T. Alem disso, há mudanças no padrão de glicosilação de glicolipídeos na superfície celular ou de glicoproteínas. Timócitos mostram uma influência de retro alimentação em células tímicas não-linfóides. Foram analisadas modificações induzidas pelo Sg em linfócitos T e células tímicas não-linfóides de bovinos. Novilhas foram divididas em 5 grupos (controle, intoxicadas com Sg durante 15, 30 ou 60 dias, e grupo provavelmente recuperado). As diferentes populações celulares das novilhas experimentais foram caracterizadas com técnicas histoquímicas, imuno-histoquímicas, lectina-histoquímicas e morfométricas. As novilhas intoxicadas com Sg mostraram uma atrofia cortical progressiva que foi caracterizada usando a lectina aglutinina de amendoim (PNA) que reconhece timócitos imaturos. Estes animais também aumentaram as células não-linfóides tímicas por unidade de área, detectadas com a técnica de Picrosirius, lectinas WGA e DBA e anticorpos antipancitoqueratina e anti-S-100. A atrofia de timo observada nos animais intoxicados foi semelhante àquela do processo de envelhecimento fisiológico. Após supressão da intoxicação, foi observado um efeito de reversão nestas mudanças. Estes resultados sugerem que a intoxicação por Sg induza a alteração observada no timo diretamente, pela ação de 1,25-dihidroxivitamina D3, ou indiretamente, pela ação da hipercalcemia.