Paulo César Raspantini

Zearalenone, an Estrogenic Mycotoxin, Is an Immunotoxic Compound

The aim of this study was to assess the toxic effects of zearalenone (ZEA) on the immune function. Ovariectomised rats were treated daily by gavage with 3.0 mg/kg of ZEA for 28 days. Body weight gain, food consumption, haemotological parameters, lymphoid organs, and their cellularities were evaluated. Moreover, acquired immune responses and macrophage activity were also assessed. ZEA promoted reduction in body weight gain, which is not fully explained by diminished food consumption. Despite no effect on haematological parameters, ZEA caused thymic atrophy with histological and thymocyte phenotype changes and decrease in the B cell percentage in the spleen. With respect to acquired and innate immune responses, no statistically significant differences in delayed-type hypersensitivity were noticed; however, in the ZEA-treated rats, antibody production and peroxide release by macrophages were impaired. The observed results could be related to ZEA activity on ERs; thus, ZEA is an immunotoxic compound similar to estrogen and some endocrine disruptors.

Experimental mitochondrial myopathy induced by chronic intoxication by Senna occidentalis seeds.

Histochemical and electron microscopic studies of biceps femoris, pectoralis major and rectus femoris of chronically treated birds with seeds of the poisonous plant Senna occidentalis (0.2% external/internal tegment), were performed. The muscles had similar features of human mitochondrial myopathy as ragged-red fibers, cytochrome-oxidase negative fibers, and weak activity of the oxidative enzymes. Fibers with lipid storage were also present. Acid phosphatase activity in rare muscle fibers was also detected, and represents probably a secondary degenerative process. By electron microscopy, enlarged mitochondria with disrupted or excessively branched cristae were seen. The present study presents a new experimental model of mitochondrial myopathy that may be useful for the best knowledge of this group of diseases and for experimental trials of drugs that could reverse the mitochondrial impairment in the mitochondrial myopathies.

The effects of low doses of Senna occidentalis seeds on broiler chickens

The effects of 0.5%, 0.3% and 0.1% w/w concentrations of Senna occidentalis (So) seed mixed with commercial ration were studied in 18 groups of 32 broiler chicks each, from 1 day to 49 days of age. Three groups were fed one of the rations throughout their lives (TL). Three other groups were fed one of the rations from the 1st to the 28th day of life (starter phase, SP), and the final 3 groups were fed one of the rations from the 29th to 49th day (finisher phase, FP). Each experimental group was matched by a control group fed the same diet over the same period but without the inclusion of So. All the animals were killed at 49 days of age, and blood was collected from 10 birds in each group for biochemical studies (ALT, AST, GGT, LDH, UA). A complete necropsy was performed on 3 birds from each group. No significant differences in the biochemical parameters in the serum were found between the control and experimental chicks, but animals treated with 0.5% So in groups FP and TL, gained less weight and chicks that received 0.3% So or 0.5% So in the ration throughout life (TL) had a larger feed conversion ratio. Besides this, degenerative changes were found in the striated skeletal muscle in the chest, in the myocardium and in the liver in the animals that received the higher concentrations of So seeds.

MUSCLE ATROPHY INDUCED IN BROILER CHICKS BY PARTS OF SENNA OCCIDENTALIS SEEDS

Senna occidentalis (formerly Cassia occidentalis) is a common contaminant of agricultural commodities. It is toxic to cattle and poultry, reportedly being responsible for skeletal myodegeneration in these animals. All parts of the plant present toxicity, but the seeds are the most toxic. The toxin(s) responsible for the myodegeneration have not been definitively identified, nor is it known which part of the seeds is most toxic. Intoxication by this plant leads to weight loss with considerable economic repercussions. The effects of the whole seed and of parts of S. occidentalis seeds (1% in commercial feed) were compared on the pectoralis major muscle of broiler chicks intoxicated from birth until 22 days of life. There were severe clinical signals and reduced body weight in birds that received the external tegment of the seed, whereas no adverse effects were observed in birds that received the whole seed or other parts of the seed. Histological and morphometric studies showed an intense muscle fibre atrophy (both type 1 and type 2 fibres were affected) in the group that received 1% external tegment. This study may be the first step to identifying the substance(s) involved in this pathological process.

Muscle degeneration in chicks caused by Senna occidentalis seeds.

Acute intoxication with Senna occidentalis seeds was studied in chicks. Seven-day-old chicks were fed ground dried seeds of this plant mixed with regular chicken ration at a concentration of 4% by weight for 15 days. Feed intake and body weight were markedly affected and a high level of lethality was observed. Necropsy examination of chicks from the experimental group revealed paleness and atrophy of thoracic muscles. Degenerative and necrotic fibres were observed in skeletal muscle by histological examination. Muscle histochemistry showed accumulation of lipids and numerous acid phosphatase-positive muscle fibres. Electron microscopy revealed atrophic muscle fibres, lipid storage, dilatation of the sarcoplasmic reticulum and abnormal mitochondria.

Effects of Senna occidentalis on chick bursa of Fabricius

Senna occidentalis (L) Link (formerly called Cassia occidentalis) is a toxic leguminous plant found ubiquitously as a contaminant of crops. All parts of the plant are toxic, but most of the S. occidentalis toxicity is found in the seeds. S. occidentalis has been shown to be toxic to several animal species, causing degenerative lesions mainly in muscles. This is the first report describing alterations in chick lymphoid organs caused by S. occidentalis seeds. The objectives of this study were to describe the effects of the treatment with seeds and its fraction external tegument (TE) on the development of chicks and their lymphoid organs bursa of Fabricius and spleen. Chicks that received a commercial ration with 1% TE had reduced body and lymphoid organ weights. The bursa of Fabricius presented reduction in the diameters of the follicles, and in the thickness of the cortical and medullary regions. The spleen presented depleted lymphoid tissue in the white pulp. These results indicate that the active principle of S. occidentalis is more concentrated on its TE fraction, and that it can cause weight loss as well as alterations in the lymphoid organs in chicks. The consequences of these alterations should be further investigated.

Evaluation in rabbits of the fetal effects of maternal ingestion of Solanum malacoxylon.

A study was performed to determine the possible toxic effects on the young of does that had been fed during the gestational period on a ration containing Solanum malacoxylon (Sm), a calcinogenic plant that contains a vitamin D3-glycoside conjugate. Experimental animals received a ration containing 0.03% or 0.04% of Sm leaves on days 6 to 30 of gestation. The levels of calcium, phosphorus and alkaline phosphatase in their sera, as well as their feed intake and body weight, were evaluated weekly. The does were euthanized 3 days after parturition and paraffin sections stained with haematoxylin and eosin were prepared from their heart, lungs, kidneys and aorta for histopathological examination. The young from does in the Sm 0.03% group were euthanized 3 days after birth and biochemical and histopathological determinations were performed, as described for the does. The does in both experimental groups showed decreased feed consumption and those in the Sm 0.04% group showed lower body weights throughout their gestation. Animals treated with Sm 0.04% presented a high incidence of abortion and stillbirth. There were biochemical and histopathological alterations in both experimental groups, which were more prominent in the does in the Sm 0.04% group. Litters from does treated with Sm 0.03% showed mineralization of soft tissue and an increase in phosphorus and calcium levels. These findings indicate that the vitamin D3-glycoside passes through the placental barrier to the fetus.

Maternal Ingestion of Ipomoea carnea: Effects on Goat-Kid Bonding and Behavior.

Ipomoea carnea is a toxic plant found in Brazil and other tropical and subtropical countries and often causes poisoning of livestock. The plant contains the alkaloids swainsonine and calystegines, which inhibit key cellular enzymes and cause systematic cell death. This study evaluated the behavioral effects of prenatal ingestion of this plant on dams and their kids. Twenty-four pregnant goats were randomly allocated into four treatment groups and received the following doses (g/kg BW) of fresh I. carnea: 0 (control group), 1.0 (IC1), 3.0 (IC3), and 5.0 (IC5) from day 27 of gestation until parturition. Dam and kid bonding and behavior were evaluated by several tests, immediately after birth until six weeks of age. Dams from IC3 and IC5 groups spent less time paying attention to the newborn. There was a lack of maternal-infant bonding due to I. carnea intoxication. Kids from treated dams had difficulty in standing, suckling, and in recognizing their mother hours after birth. I. carnea can also compromise the kids’ ability to learn and to retain spatial memory. We suggest that kids from pregnant goats given I. carnea during gestation have significant behavioral alterations and developmental delays that may compromise their survival.

Assessment of the perinatal effects of maternal ingestion of Solanum malacoxylon in rats

A perinatal study was performed to verify the toxic effects of Solanum malacoxylon, which contains a glycoside conjugated to Vitamin D(3). In the gestational study, female rats received S. malacoxylon leaves in the diet at 0, 0.1, 0.2, 0.5, and 1% from days 6 to 21 of pregnancy. At 21 days of gestation, blood samples were taken from the dams for evaluation of serum Ca and P. A laparotomy was performed and the rats were examined for standard parameters of reproductive performance. Fetuses were examined for skeletal changes and histopathologic evaluation. In the second trial, dams were fed diets containing 0 or 0.1% S. malacoxylon leaves during the gestation and lactation periods. After weaning, all animals were euthanized and biochemical and histopathologic evaluations were performed. The biochemical evaluation showed increase in Ca and P levels in females from all experimental groups; however, this effect did not occurred in a dose-related manner. Pups from dams exposed during gestation and lactationi also showed increased Ca and P levels. Fetal data suggested a delay of fetal development manifested by decreased body weight and skeletal alterations. There was also a reduction in live fetuses. Histopathologic study revealed alterations of the soft tissue in litters from dams given 1% dietary S. malacoxylon during pregnancy and 0.1% during pregnancy and lactation. These findings support our hypothesis that Vitamin D(3) glycoside crosses the placenta and suggests milk transfer of this substance.

Low doses of monocrotaline in rats cause diminished bone marrow cellularity and compromised nitric oxide production by peritoneal macrophages

Monocrotaline (MCT) is a pyrrolizidine alkaloid found in a variety of plants. The main symptoms of MCT toxicosis in livestock are related to hepato- and nephrotoxicity; in rodents and humans, the induction of a pulmonary hypertensive state that progresses to cor pulmonale has received much attention. Although studies have shown that MCT can cause effects on cellular functions that would be critical to those of lymphocytes/macrophages during a normal immune response, no immunotoxicological study on MCT have yet to ever be performed. Thus, the aim of the present study was to evaluate the effect of MCT on different branches of the immune system using the rat – which is known to be sensitive to the effects of MCT - as the model. Rats were treated once a day by gavage with 0.0, 0.3, 1.0, 3.0, or 5.0 mg MCT/kg for 14 days, and then any effects of the alkaloid on lymphoid organs, acquired immune responses, and macrophage activity were evaluated. No alterations in the relative weight of lymphoid organs were observed; however, diminished bone marrow cellularity in rats treated with the alkaloid was observed. MCT did not affect humoral or cellular immune responses. When macrophages were evaluated, treatments with MCT caused no significant alterations in phagocytic function or in hydrogen peroxide (H2O2) production; however, the MCT did cause compromised nitric oxide (NO) release by these cells.