Prosopis juliflora is used for feeding cattle and humans. Intoxication with the plant has been reported, and is characterized by neuromuscular alterations and gliosis. Total alkaloidal extract (TAE) was obtained using acid/basic-modified extraction and was fractionated. TAE and seven alkaloidal fractions, at concentrations ranging 0.03-30 microg/ml, were tested for 24h on astrocyte primary cultures derived from the cortex of newborn Wistar rats. The MTT test and the measure of LDH activity on the culture medium, revealed that TAE and fractions F29/30, F31/33, F32 and F34/35 were cytotoxic to astrocytes. The EC(50) values for the most toxic compounds, TAE, F31/33 and F32 were 2.87 2.82 and 3.01 microg/ml, respectively. Morphological changes and glial cells activation were investigated through Rosenfeld's staining, by immunocytochemistry for the protein OX-42, specific of activated microglia, by immunocytochemistry and western immunoblot for GFAP, the marker of reactive and mature astrocytes, and by the production of nitric oxide (NO). We observed that astrocytes exposed to 3 microg/ml TAE, F29/30 or F31/33 developed compact cell body with many processes overexpressing GFAP. Treatment with 30 microg/ml TAE and fractions, induced cytotoxicity characterized by a strong cell body contraction, very thin and long processes and condensed chromatin. We also observed that when compared with the control (+/-1.34%), the proportion of OX-42 positive cells was increased in cultures treated with 30 microg/ml TAE or F29/30, F31/33, F32 and F34/35, with values raging from 7.27% to 28.74%. Moreover, incubation with 3 microg/ml F32, 30 microg/ml TAE, F29/30, F31/33 or F34/35 induced accumulation of nitrite in culture medium indicating induction of NO production. Taken together these results show that TAE and fractionated alkaloids from P. juliflora act directly on glial cells, inducing activation and/or cytotoxicity, stimulating NO production, and may have an impact on neuronal damages observed on intoxicated animals.

Prosopis juliflora was introduced in northeastern Brazil in the 1940s, and since then, it has been available as an alternative for animal nutrition. However, the consumption of P. juliflora as main or sole source of food causes an illness in animals known locally as "cara torta" disease. Cattle and goats experimentally intoxicated presents neurotoxic damage in the central nervous system. Histologic lesions were mainly characterized by vacuolation and loss of neurons in trigeminal motor nuclei. Furthermore, mitochondrial damage in neurons and gliosis was reported in trigeminal nuclei of intoxicated cattle. Studies, using neural cell cultures, have reproduced the main cellular alterations visualized in cara torta disease and contributed to understanding the mechanism of action piperidine alkaloids, the main neurotoxic compound in P. juliflora leaves and pods. Here, we will present aspects of the biological and toxicological properties of P. juliflora and its pharmacologically active compounds.

A Prosopis juliflora é amplamente utilizada na alimentação humana e de várias espécies animais, especialmente bovinos. Quadros de intoxicação por esta planta, nesta espécie, têm sido relatados, principalmente quando a mesma é oferecida como única fonte alimentar, desencadeando uma doença de sintomatologia nervosa. Neste estudo, objetivou-se avaliar os efeitos in vitro da fração de alcalóides totais (FA) extraída das vagens da Prosopis juliflora utilizando cultura primária de astrócitos obtidos do córtex cerebral de ratos como modelo de estudo. A avaliação da atividade mitocondrial pelo teste do MTT demonstrou a citotoxicidade em 30 µg/ml da FA após 24 h. As concentrações de 0,3 e 3 µg/ml da FA induziram um aumento da atividade mitocondrial, indicando reatividade celular. Testes imunocitoquímicos para a GFAP, principal proteína de citoesqueleto de astrócitos, revelaram alterações morfológicas nas células após tratamento com 0,3 e 3 µg/ml da FA por 72 h. Tais resultados são consoantes à análise desta proteína por westernblot, quando as culturas foram tratadas com 0,3 e 3 µg/ml da FA por 72 h, demonstrando interferências na regulação da expressão da GFAP. A expressão de vimentina não foi significativamente alterada em nenhuma das concentrações testadas. Estes resultados sugerem que os alcalóides da P. juliflora induzem a reatividade astrocitária, o que pode estar envolvido nos efeitos neurotóxicos providos pelo consumo desta planta.